O.K.
This is just from research, and I haven't checked by pulling the BM54 out for a look yet.
From earlier in this thread, it is indicated that the EEPROM chip is a 29F400. This appears to be available in either of TSOP48,PSOP44 package formats. Data sheet for the chip is attached. (i think!!!, I'm not yet proficient at attaching files to posts
). If not, google Atmel 29F400.
I've been looking at Ebay for programmers, and found this one which should do the trick (no guarantees, do your assessment) but you will also need an adapter from the same source for the TSOP48 or PSOP44 package. They are listed in his Ebay store.
True USB Willem EPROM BIOS FLASH universal programmer (eBay item 310291769368 end time 30-Mar-11 05:10:24 AEDST) : Industrial
I would suggest burning to a new fresh 29F400 so that you have the old one to go back to if something goes wrong.
If you go ahead with this, can you post back to let everyone know, as it will probably be a couple of months before I can get around to it.
Good Luck!!