HHKB Pro2 custom controller

I have a happy hacking pro 2 keyboard that I like very much. One of the few gripes I have is that even with a usb to ps2 adapter, it is incompatible with ps2. My understanding is that the issue is with the default controller in all topre keyboards and that HHKB are fairly easily modded with custom controllers. But for the time being my internet access is solely through my phone, which makes doing proper research difficult. So just wondering if there was anyone familiar with modding HHKbs that could point me to an appropriate product.