Have you looked into rasdial?
Just incase anyone wanted to do this and finds this in the future, you can use rasdial.exe from command prompt to connect to a VPN network
ie
rasdial "VPN NETWORK NAME" "Username" *
it will then prompt for a password, else you can use "username" "password", this is however less secure
http://www.msfn.org/board/topic/113128-connect-to-vpn-from-cmdexe-vista/?p=747265