Well the UART jack is a RJ-45/12 with 8 conductor connections. Minium UART requires TX, RX and ground connections. You need to know which?connector on the plug gets which signal. Here's the pin outs.?
Easy to make if you?have a RJ plug crimper. I paid $40 for mine in the day.?Under a tenner now. I'd go for a Molex or Dupont type 6 position plug at the?usb to serial adapter. I have another crimper for these but you can get away with needle nose pliers. I generally use Dallas Labs or CKH adapters because they broke the FTDI monopoly and got prices down to under $2.