or has anyone tried using a regular USB to UART adapter?
One user modified an old Block Erupter USB (those small things that plug straight into a USB port) to work with a Block Erupter Prisma;
[DIY] Tube/Prisma USB Adapter from USB BlockerupterHe notes:
You should theoretically be able to use any CP2102 USB-UART witha 1K pullup resistor from 3.3V to RXD in this fashion.
YMMV