Change the Default Gateway on a VPN

Hello,

I've a similar question to nareen123 on http://ccm.net/forum/affich 13513 how to change ip address from command prompt.

I want to change the Default Gateway of a connection on Windows XP with SP3. But the Connection is a VPN!

From ipconfig the connection is:
PPP adapter tdp:
Connection-specific DNS Suffix . :
IP Address. . . . . . . . . . . . : 10.70.0.62
Subnet Mask . . . . . . . . . . . : 255.255.255.255
Default Gateway . . . . . . . . . : 10.70.0.62

The commando should be this one:
netsh interface ip set address "PPP adapter tpd" static 10.70.0.62 255.255.255.255 10.70.1.244 1

The result is: ""Invalid interface PPP adapter tdp specified""

The problem is that netsh doesn't include the VPN interface! It only includes the physical interfaces I have. When I run the command:
netsh interface ip show config

It doesn't list the "PPP adapter tdp" has ipconfig command lists.

How can I then, change the Default Gateway of the VPN??

All this work is off course because It's not possible to change the default gateway in the normal gui interface. And I need to Change it.

Thank you very much in adavance!