Hello Timothy,
will the citrix farm be accessed only by specific IP ranges of your office or through internet also ? If it will be accessed by your remote offices only , then you can do the following:
terminate the second link on the dmz interface.. i assume that the main link is on the ouside.. have the default route on the outside interface for internet access. you would have already dont a PAT for the inside users with the IP address of ISP 1 for this case.. You can then NAT the citrix IP onto the DMZ interface with ISP 2 IP address... You can add static routes for the remote offices throgh the second router on the DMZ...
If it is going to accessed by guys in internet also, then i dont think PIX supports multihoming !!! you have to use a router on the external interface to run BGP and get multihoming done !!!
Hope this helps.. all the best.. rate replies if found useful..
Raj