Ok, I'm sure Greg (greolt) or "poppabear" will be along to help with this shortly, but here's my code (which is like Gregs):
Woah!!!! I don't think my name should be mentioned in the same breath as Poppabear's

I have to ask him the most basic questions.

And I have never seen that code before. Never even tried centring routines before.

Phill what code are you asking about? Can you open it in an editor? Look for an F command and change it to what you want.
If it has none then G31 will use the last used feedrate. But adding a line should be no problem.
Also see the following two line in Budman's code,
FeedCurrent = GetOemDRO(818) 'Get the current settings This one near the sart
Code "F" &FeedCurrent 'restore starting feed rate This one near the end
They restore the feedrate to what it was before running the routine.
Greg