The pinout is:

RJ - DB
3 - 3
4 - 2
5 - 5

If you have a connector that lets you program from the terminal it should work for VM connection. You can also test it by putting it on a laptop and seeing if you can get into programming. If you switch is a 1632 you should be hooked up to the 3rd rs-232 port. Also you might want to check the your baud rates match on the switch and VM.

[Linked Image from commsmith.com]