From reading the document on cisco it appears all I have to do is add these two lines
access-list 101 permit ip <my internal ip address of my PIX> 255.255.0.0 <.0 of the starting range of my pool 192.168.123.0 ?? > 255.255.0.0
vpngroup specialusers split-tunnel 101
access-list 101 permit ip <my internal ip address of my PIX> 255.255.0.0 <.0 of the starting range of my pool 192.168.123.0 ?? > 255.255.0.0
vpngroup specialusers split-tunnel 101