The signalink's a great piece of gear, but all one really needs is a audio cable and some audio transformers and the requisite connectors for each end. Just plumb the audio ins and outs, passing each via a xformer to isolate the circuit and then employ vox to do the tx/rx switching. You can go in via the mic or the 8 or 13 pin din common to almost every icom, even the mic has audio out.