Not that I know of. As you've probably heard, the process of updating the ROM reads the ROM image from the CF card and clears the RAM in the process. Though it seems unlikely to work, I haven't tried (or heard of anyone who has tried) to update the ROM from the RAM.
The only obvious changes to the ROM that have been discussed are a fix for the speaker pops and a fix that makes sure the alarms go on when they should. The speaker does 'work', but depending on the source of the sounds, to varying degrees it will pop. Hopefully, these issues can wait until you have a CF card.