I mean, it is able to work, but I don't have music on it. I'll try your suggestions if you can explain the first bullet and what sudo is.
I'm not sure if I understand you correctly. Did you get Rockbox running on the Ipod? If you already have the bootloader installed these tests are pointless.
Dumping the partition table is done similarly as writing the partition table in the IpodConversionToFAT32 wiki page. The command would look like dd if=/dev/diskN of=mbr-xxxx.bin count=1 bs=512
The same way described on the wiki you need to replace the N with the disk number of your Ipod and the mbr-xxx.bin with an arbitrary file name.
Sudo is a tool for running a program with elevated permissions -- while started from a user account a program can get root permissions (see http://developer.apple.com/DOCUMENTATION/DARWIN/Reference/ManPages/man8/sudo.8.html for details). It's called from the command line. Open a terminal and type something like this: sudo /path/to/rbutil-binary
Not sure where to find the binary on OS X -- perhaps someone else can give details here. Another interesting test would be to try if bootloader installation works on Windows.