Mouse not reconfigurable

Well, am used to walk/run with Mouse right-click button - I never had to go thru a game which would prevent me from doing so - GW is the first which does not let the mice buttons to be reconfigured - I think this plain sucks personally...

However I noticed that if you pressed BOTH right and left click buttons, you can then move around and run/walk at the same time - pressing 2 buttons at the same time is not good - would have like to have freelook+run configured on right-click mouse button...

Has anyone been able to do that or have I read it well in the first place?

Thanks in advance