[FW1] SecuRemote behind NAT / Firewall

[Merlin]

Afternoon,     I have to allow some sales reps through our firewall (chkpnt 4.1) so they can telnet to a Unix System for business purposes. On some of those reps, securemote works fine since they are using routable IP addresses. But others have DSL firewall or NAT devices and although I have tried the suggestions found at phoneboy.com it still doesn't allow access. Is there another way to let them through that uses some sort of encryption? Thanks again.