Since I always like to have NEC firmwares with full bitsetting support, I decided to modify the NEC 3540 firmware version 1.01 and add the bitsetting code from a MadDog 3520 firmware.
Please consider that this is a highly experimental firmware that may still have some bugs. If you damage your drive by flashing this firmware, neither me nor CD Freaks can be held responsible for this damage. Don't RMA your drive in this case, but buy a new one.
Download NEC ND3540 1.01 Bitsetting firmware here. Three files are included in the archive, containing a version only with added support for bitsetting, a fast version removing riplock and a version with RPC1. None of the firmwares contains write strategy changes.
In order to flash these firmwares you need to use a firmware flasher that is compatible with NEC ND3540A drives. Binflash supports these drives since version 1.16.
Please remember that the booktype for your drive can only be changed when no disc is inserted!
[EDIT]Download disabled. Had some issues with flashing[/EDIT]
[EDIT2]Uploaded a new version based on a different 1.01 firmware. Thx@Dee-27 for the base firmware[/EDIT2]
[EDIT3]Another new 1.01 firmware. The previous one can still be found here.[/EDIT3]
[EDIT4]Yet another 1.01 firmware. Old NEC 3540 bitsetting firmware here[/EDIT4]