If you learn quickly, I expect that you could learn how to do it relatively soon. That said; I would suggest that you should do this firstly as a project and once you have got a good working knowledge of php/perl, and mysql then you might think of offering it to real customers.
If however, it's your own company, then you perhaps could do it alongside the live site and when tested and working, re-point the domain name or re-lable the home pages so that the new one takes over.
Of course, if you are willing to learn there are plenty of people here at CF who will offer help if you ask in the other forums.
"The day you stop learning is the day you become obsolete"! - my late Dad.
Why do some people say "I don't know for sure"? If they don't know for sure then, they don't know!
Useful MySQL resource
Useful MySQL link