I have seen a few hacked BIOS versions (or even officially unlocked- after the warranty ended naturally) for some of the low volume system builders like emachines over the years.
Trouble is Dell are big enough to have their own motherboards built and they frequently do so should you manage to find the model it was initially based on, get the original BIOS in a workable shape and likely dodge signing if it is a dell you are still likely to be looking a low spec piece of junk for a motherboard (there is a good reason Dell have a bad name in system building/performance computing circles).