connect sdi and sdo and together
You want to directly interface the sensor through the usb, or you can afford to implement a small PIC to be the interface?
If you can use the PIC, it is very simple... The sensor should be able to be set to continiusly send info on the temperature to the PIC via SPI, and all you need to do is to forvard that data to the DLP using standard serial protocol. Using a PIC that have internal UART makes this very simple.
If you don't know how to write ap rogram for PIC, I can help you with it.