Different IP for different users

Someone knows if on XP Professional it's possible to force that ip
traffic, originated from different users contemporanely acive (fast
user switch is active), has different ip addresses, maybe forcing the
physical output interface even if it isn't a must.
Probably it's a little strange request and I'm not pretty sure that it
is really possible (pheraphs in theory...) but I thinked to ask to
someone with better knowledge than me before to surrender to evidence.

Thanks.
Best Regards,
Simone Navari
.