Go back to the manufacturer for spares. There are Legal and Safety issues involved here. There are reasons the microcode is protected over and above simple replication. If you tamper with the microcode you potentially threaten the lives of the people using the elevator... and if you are competent enough to make such modifications, then you are competent enough to write the elevator code in it's entirity from scratch and then have it independantly certified and tested for safety before it is put into service. Personally I'm not willing to risk serious jail-time (nor would I recommend others to do so) in order to save you a few dollars.