Hi,
The CONFIG registers aren't (normally) accessible at runtime like "normal" registers. You can change them by using you device programmers software (which programmare are you using?) or you can set/change them in the code. The way you set them in code depends on which version of PBP you're using.

If you're using PBP3 then open up the manual and read up on the #CONFIG / #ENDCONFIG directives. If you're using a version prior to PBP3 then make sure you read this thread. Or you can search around the forum a bit and you'll find PLENTY of information since CONFIG settings are one of the most discussed topics.

/Henrik.