If you use the /AutoPPP/ option for automatically creating a ppp 
connection, the user name does not appear in the who list. Instead,
something like AutoPPP or ppp is displayed. Solution: you have to
patch pppd, that's not mgetty's issue and thus can't resolved patching
mgetty. 
If you have the patched pppd, this is how it works. You have
to add the option "login" to pppd in login.config and change the third
column to "-" (in the example it's a_ppp or ppp).