Changing MSGINA.DLL (Windows logon Dialogue)

I'm looking to change the logon dialogue box in Windows XP Classic logon. The
dialogue currently has an option at the bottom for starting a dial-up
connection before logon. I need to change this to launch a Cisco VPN
connection first.

I can modify the text to show "Logon using Cisco VPN Client connection" but
I can't find anywhere to change the executable "VPNGUI.EXE" to run if this
control is ticked. I'm using reshacker to modify the dll and suspect I can
only do text and graphics with it.

Can anyone point me in the right direction to perform this mod please? Any
comments greatly appreciated.

Nigel