Howto establish ipsec vpn connection using rasdial.exe?

Hello,

I hope i post this to the right group. Please let me know where to post it
otherwise:

I know I can establish a vpn connection using rasdial.exe with an according
rasphonebook.

But I want to automatically establish an IPSec VPN connection and need to
provide the preshared key for it.

RASDIAL.EXE itself doesn't provide a parameter for the preshared key.

So I assume that the preshared key can somehow be provided in the
rasphone.pbk file.
But where and how?

Or is there antother way to do this?

Many thanks in advance for every hint.

Roberto Rocco.