Hi Jorge,
yes you can do it. Here's an excerpt from our PIX running 6.3(5)
Notice the different VPN groups - details changed :)
vpngroup A address-pool A
vpngroup A dns-server x.x.x.x
vpngroup A default-domain DOMAIN
vpngroup A idle-time 1800
vpngroup A password AAA
vpngroup B address-pool B
vpngroup B dns-server x.x.x.x
vpngroup B default-domain DOMAIN
vpngroup B split-tunnel NONAT
vpngroup B idle-time 1800
vpngroup B password BBB
access-list NONAT permit ip 255.255.255.0 255.255.255.240
If I were you I'd create a new address pool just for that user, which will allow for scalability if more road warriors come into the frame. Any additional can then be placed into the same vpngroup
HTH
Ali