What custom firmware works with Asus WL-520g? (Note this is not 520gU, 520gC, etc.)

I failed to flash it with Tomato (Tomato_1_28_ND.zip) - the admin UI does not accept the file, and when trying to tftp the file as adviced for 520gU all I get is this:

Transfering file tomato-ND.trx to server in octet mode...
Error occurred during the file transfer (Error code = 0):
Error in SendPacket() call.

I just saved the router form rather unsuccessful flash to DD-WRT (after few hours the router fell into coma), and I'd like to keep it as a backup should the new one die or whatever. (Unfortunately the stock firmware does not support WOL.)