Seems easy to make something similar to the
Deneb PCB (warning big image!). It's a Xilinx XC2S50 speedgrade 5C. In essence the simplest the FPGA Xilinx has, it may even be out of manufacturing.
The large chip at the top-right is unreadable. But it's likely an USB interface chip. The smaller chip to the left-middle is however a question.
In essence DENEB seems to be a simple FPGA, USB interface and support circuitry like boot-EEPROM and power. So it's not that hard to make a replacement. Driver compatibility may be an issue though.
Creating a cable to upgrade the on-board EEPROM should be that hard either.