They aren't actually "linux compatible". They require you to use their software to connect, and their debian package will only work on Lindows. I am using a program called RASspy that tells you your real username and password. You would write your normal username and password into the NetZero software like
user@netzero.net and password doggytreat, but this will show you the REAL username, and it will be something like lidhe394.HQ2:username@netzero.net and password 934$2$!49.
I will look for the modem log in the directories you listed. Do you have an idea of what the file might be called? I searched for "modem" and "modemlog" but it didn't find anything.
Thanks!