Here's what the Roman Catechism says:-
[35. Adulti quomodo ante Baptismum instruendi sint.]Diversam vero rationem in iis servandam esse, qui adulta aetate sunt, et perfectum rationis usum habent, qui scilicet ab infidelibus oriuntur, antiquae ecclesiae consuetudo declarat. Nam christiana quidem fides illis proponenda est, atque omni studio ad eam suscipiendam cohortandi, alliciendi, invitandi sunt. Quod si ad dominum Deum convertantur, tum vero monere oportet, ne, ultra tempus ab ecclesia praescriptum, baptismi sacramentum different. Nam cuм scriptum sit: Non tardes converti ad Dominum, et ne differas de die in diem; docendi sunt perfectam conversionem in nova per baptismum generatione positam esse. Praeterea, quo serius ad baptismum veniunt, eo diutius sibi carendum esse ceterorum sacramentorum usu et gratia, quibus christiana religio colitur, cuм ad ea sine baptismo nulli aditus patere possit: deinde etiam maximo fructu privari, quem ex baptismo percipimus; siquidem non solum omnium scelerum, quae antea admissa sunt, maculam et sordes baptismi aqua prorsus eluit ac tollit, sed divina gratia nos ornat, cuius ope et auxilio in posterum etiam peccata vitare possumus, iustitiamque et innocentiam tueri: qua in re summam christianae vitae constare facile omnes intelligunt.
[36. Adultis baptismum differendum esse demonstratur.]Sed quamvis haec ita sint, non consuevit tamen ecclesia baptismi sacramentum huic hominum generi statim tribuere, sed ad certum tempus differendum esse constituit. Neque enim ea dilatio periculum, quod quidem pueris imminere supra dictum est, coniunctum habet;
cuм illis, qui rationis usu praediti sunt, baptismi suscipiendi propositum atque consilium, et male actae vitae poenitentia satis futura sit ad gratiam et iustitiam, si repentinus aliquis casus impediat, quo minus salutari aqua ablui possint. Contra vero haec dilatio aliquas videtur utilitates afferre. Primum enim, quoniam ab ecclesia diligenter providendum est, ne quis ad hoc sacramentum ficto et simulato animo accedat, eorum voluntas, qui baptismum petunt, magis exploratur atque perspicitur: cuius rei causa in antiquis conciliis decretum legimus, ut qui ex iudaeis ad fidem catholicam veniunt, antequam baptismus illis administretur, aliquot menses inter catechumenos essent: deinde in fidei doctrina, quam profiteri debent, et christianae vitae institutionibus erudiuntur perfectius. Praeterea, maior religionis cultus sacramento tribuitur, si constitutis tantum paschae et pentecostes diebus, solemni caeremonia baptismum suscipiant.
Ref: Catholic Church (1566) Catechismus ex Decreto Concilii Tridentini ad Parochos Pii Quinti Pont. Max. Iussu Editus. (Rome: Manutius) pp.197-198.
http://books.google.co.uk/books?id=TPxbAAAAQAAJHeadings from the 1845 Rome edition. p.108 ff.
Here's my translation:-
[35. How adults should be instructed before baptism.]The custom of the early Church testifies that a truly different method is to be kept for those who are at a mature age and have the complete use of reason, and for those who undoubtedly descend from infidels. For instance, the Christian faith is at least to be proposed to them, and they are also to be exhorted, drawn and invited to take it up with all zeal. If they are converted to the Lord God, then truly it is proper to advise them not to put off receiving the sacrament of baptism beyond the time prescribed by the Church; for seeing that it is written: Do not delay to convert to the Lord, and do not postpone it from day to day, they should be taught that complete conversion, by a new coming into being through baptism is, to be highly valued; in addition, those who come late for baptism, still further lose for themselves the advantage and the grace of the other sacraments with which the Christian religion is adorned, since, without baptism, no one can be permitted to approach them [= the other sacraments]; then also they are deprived of the chief reward which we secure from baptism; because not only does the water of baptism wash off and entirely take away the stain and uncleaness of every evil deed which they had previously committed, but it adorns us with divine grace, by whose power and assistance we are also able to avoid sins in the future and to safeguard [our] righteousness and innocence; which, in reality, all easily understand to be the chief point of the Christian life.
[36. It is shown that the Baptism of adults is to be delayed.]But nevertheless the Church has not been accustomed to bestow the sacrament of baptism at once upon this kind of person, whomsoever they might be, but has appointed that it should be deferred to a fixed season. Nor, in fact, does that delay hold the associated danger, which was said above to be certainly imminent for children, since,
for those who are endowed with the use of reason, the intention as well as the resolution of receiving baptism, and repentance for a life badly spent, would be sufficient for the grace and the righteousness [of baptism to be granted to them], if some sudden accident should impede them from being able to be washed in the water of salvation. Indeed, on the contrary, this delay seems to bring certain advantages. In the first place, in fact, because it is carefully provided for by the Church that, lest anyone approach this sacrament with a feigned and simulated spirit, the desire of those who seek baptism is, to a greater extent, investigated as well as observed, on account of which we read in ancient decrees of the Councils that those who come to the Catholic faith from the Jews, shall spend several months amongst the catechumens before baptism is administered to them. Then, they are to be completely instructed in the doctrine of the faith which they ought to profess, and in the institutions of the Christian life. Moreover, a greater degree of reverence is shown towards the sacrament, if it be arranged that, they receive baptism with solemn ceremony only on the days of Easter and Pentecost.
In brief, the Roman Catechism DOES teach what has since acquired the term "baptism of desire", but only in respect of adult catechumens who die before being baptised at the proper season for receiving the sacrament. See the part that I have underlined.