The military offers online knowledge centers regarding various IT areas, however as far as hands-on training or even certifications, if you are not in that career field (I unfortunately am not) you are not going to get that training.
You just need appointment orders for most of the training after AIT. I know Information Technology Specialist (25B) that are worthless & Human Resources Specialist (42A) that seem to know too much for their own good. Commanders know it and they're the ones that sign appointment orders. You might not be in a situation that allows you the chance but don't think it doesn't happen. I"ve seen good 25Bs end up being commanders drivers and shitty/lazy ones doing paperwork and/or forced to work on the night shift.
Online isn't your only option right now & neither is college. Experience/hands on, certifications and degrees are all important. Either one could make or break your chances of getting a job... depending on the employer, type of job and your competition. Books and certs like A+, N+ & Security+ will do a lot of good. The market is looking for everything. Those basic certs will help you find out what you enjoy doing too. Its true that Server admins, Web page designers, Network admins and Database admins all need different & specific training but basic certifications help all of them... especially when they have no prior experience or training.
Don't forget the power of networking while you're in the military either. Knowing the right people/person can guarantee you a federal job or even a nice contractor position. They can send you to the schools you need and couldn't attend before.