I’ve been actively involved with apologetics on an amatuer level for about 20 years. As far as I know there is no formal program or certification for Catholic apologetics like there is at Biola College for Evangelical Protestants. It is something I’ve always wished that a good, orthodox Catholic University (like Stubenville, or Catholic Distance Universty, for example) would offer, perhaps online. As it is, the only way to become an apologist is to engage in it. We are all called to be able to defend our Faith if necessary (1 Peter 3:15), but one can take it a notch higher and actually make it a ministry, getting involved in parish work (RCIA, etc) where you have the chance to teach and clear up misconceptions and give people tools and “ammunition.”
The next higher level is ministry outside and/or with the parish, still as an amatuer (i.e., just for the sheer love of it), perhaps starting a chapter of Catholics United for the Faith and concentrating primarily on apologetics, teaching others, offering to give talks and helping to bring nationally known apologetics speakers to your area. Again, this is in your spare time and is done as a sacrifice of love.
The last level is to be in full time apologetics work where it is basically your occupation. The most well known Catholic apologists have a varied background: former Protestant ministers, laymen with no formal theological background, lawyers, police officers, etc, etc. None of them have had any formal training in Catholic apologetics–driven by a love of the Faith, they have all learned by hours of study and prayer, and by going out there and actively defending the Faith.