I used BitPim over a bluetooth connection, I don't believe that BitPim currently supports this phone properly, but in generic mode, I have dumped wallpapers into the /brew/mod/10888/ folder. you will need to edit "Default Album.alb" manually, and then re-upload that to your phone.

You can access the wallpapers from Multimedia > My Images

From here, you can set them as Caller pics, or wallpapers.

Same thing applies for ringtones, I successfully dump those into the /brew/mod/18767/ folder, you will have to edit that .db file as well, to match your mp3's. The mp3's can be accessed from Multimedia > My Sounds, and can be set as ringtones.

After editing these files, you may need to power off the phone and back on, but this should allow you to add wallpapers and ringtones.

I can't remember the link offhand, but there's a more detailed tutorial (for the mp3 ringers) on several forums, including this one. as far as the wallpapers, I haven't seen a tutorial on this, but it's similar in fashion to the mp3 ringtones, although the file that needs to be modified has a different format, they're readable with any good text editor.

Managed to get into file system with Bit Pim by setting PC connection to USB modem.
But the shared folder in Brew comes up blocked by provider so don't know how to get ring tones into phone yet.
Any ideas?