PPTP Wake On Lan User Start XP

Can a Wake On Lan call start a user in XP.

I have a XP machine with 3 users.
I have Wake On Lan NIC card installed connected to a router.
I have a palm phone device with PPTP capability.

I am able to access the PC and establish a remote connection with the palm
device when a user is logged on the PC. I am able to remotely bring the PC
out of hibernation and establish a remote PPTP connection.

I can get the PC to Wake On Lan remotely from a cold start but I can't get
past the user Log In screen...

Does any one know how to remotely start a user on an XP machine (from cold
start) and also what Magic Packet is used to Shut Down the PC remotely ?

Thanks awfully for advice

Ian