Hello world! I haven't been able to find this online anywhere, so here it is for those who may find it useful...
jailbreakme.com apparently breaks Mobile Terminal. This means you will have to change the passwords from your PC using an SSh client like Putty, etc. (I tried installing an older version of Mobile Terminal via the deb file, but no worky.) Another way to get terminal access is to use a SSh client for iDevices like TouchTerm, iSSH, etc. and simply SSh to localhost! This works awesomely for port scanning after installing nmap!
Oh, and there's also a very cheesy and very free iPhone SSh client called Mobile Admin also available from the Apple app store which you can use for this. Strangely enough, however, you must SSh to the loopback address of 127.0.0.1 because it can't resolve the hostname localhost.