telnet source IP
You could add a static route to the host you are connecting to.
For example...
You connect to 10.10.6.5
Interface 1: 192.168.1.50/32
Interface 2: 192.168.2.50/32
Default gateway: 192.168.1.1
Static route for 192.168.2.0/24 to 192.168.2.1
If you want to connect to 10.10.6.5 via 192.168.2.1, you add this static route:
route add 10.10.6.5 mask 255.255.255.255 192.168.2.52
on linux, it's
telnet -b source-ip dest-ip
to "bind" to a different interface