It doesn't look too hard. I would create a new DEFINE (DEFINE OWINV 1 ?) if I were you. That way you can use the same library - inverted or not.
I did nearly the same thing with DEBUG. I have a define that lets me run DEBUG in an open-collector mode - useful for high-speed serial networking
between PICs.

I can give you some hints this evening, but I don't have any OneWire devices to test.