I did with my machines...

I have two notebooks. One is allowed to login to a client through VPN but at my new client site the VPN is always blocked and I can't ask the new client to open up a port for the connection. So what I do is -

(1) With the first notebook to log to target (old) client from home
(2) At new client site I login to my home notebook from 2nd notebook with Logmein or Gotomypc
(3) I can do whatever in the 2nd notebook at new client site through 1st notebook just like I am sitting in front of first notebook.