Not sure if that works.

I think if you use a hex editor (like u-edit) on xolox.exe, you can simply replace any occurances of:
www.xolox.nl

with something like

localhostxxx

Then you wouldnt have to do anything to your firewall or anything. just fire up xolox as you normally would.

This may be what was done in that crack thats floating around, but im not sure. Anyone try this?