I haven't been able to mount anything in any directories except /tmp. That's because the entire filesystem is mounted read-only except for the /tmp directory. Some of the directories are linked to directories under /tmp to make them writeable.
Try this if you have a windows share:
mount -t smbfs -o username=SomeUser //ShareComputer/MP3Share /tmp/mp3
Where SomeUser is the name of a user on ShareComputer.
You may get an error message saying something about a missing codepage or something. You need to search the internet for the file unicode_map.850 and put it in /etc/codepages