Maybe the firmware is hackable. Is it in a potted chip?
As an alternative, I have a pair of SureFlap catflaps on their way here. Those things are a bit more expensive - I scored them at 59 euros a pop - but highly hackable for use as access control devices: essentially, once you remove the catflap door and soldered a relay to the door latch line, you have a very good FDX and EM reader with 32 programmable authorized tags in a convenient case with a battery holder, and at least a year of battery life with 4 AA cells.
One of them will open my minivan soon. I’ll post a howto when I get them.
Ah right, I didn’t know that.
On the other hand, the convenience factor is huge: it’ll open with many transponders out of the box without any programming