If Tony connected the part using the SMBus, then he could possibly use motherboard monitor to read the temperatures. It looks like the MAX6654 is supported by motherboard monitor.

Otherwise, it would be safer to just drive it from the serial port. It is pretty trivial to set the flow control pin from VB to bit bang the data. A transistor would be needed to mux the data to read the ACK, though. Power could come by feeding off the keyboard connector.