Well, first I'd get a compatible pascal compiler. And no matter what you get, there's sure to be 'issues'.
If it's a 'processing' program, you're still going to have to contend with how data gets in and goes out of the program, that may bring up different issues on a PC than on a Mac.
If you mean a GUI program watch out. Delpi had a program to let PC stuff run on a unix type platform, but I would suspect that a lot of it is an interface layer that assumes you start on the PC and then does some kind of translation to a unix interface layer. Sorry, but I don't really know. I've got the package in a drawer somewhere but never used or even installed it.
I would say your best bet is to contact the language vendor for the package you're now using and see what they offer. Then decide.
If it's REALLY bad, and you have to manually do it, I'd set up a PC and a Mac next to each other, start by copying the screens, and then doing it event by event for the screen items. Won't be simple.
