We have the same issue. One idea I had was to create a self-service item
which runs a script which rungs the mobileconfig file which then asks
for the username and password...similar to what happens if you run the
mobileconfig file on the desktop.
Like the nice man said...any advice and points would be greatly
appreciated, by me as well. On our side we are trying to install a IKEv2
profile but using username and passwords.