Many Icom radios can use a CT-17 CI-V level converter to connect up tp 4 radios to a PC for PC controll of those radios. This lead is the one that connects the CT-17 to the radio. It is also used by some Icom models (IC-9100 springs to mind) as a cloning lead for copying data from one radio to another.
Before you start have you got a 3.5mm mono or stereo to 3.5mm mono or stereo jack plug intrerconnecting lead? (mono to mono is preferred but stereo to stereo will work, don't try a stereo to mono lead though as it may short out the required signals). If so you can use that. If not read on and make this really easy-to-make lead.
Assemble as shown diagrammatically below. Use the shield of the cable (if shielded) for the outer (Black) connection and don't forget to put the covers of the jack plugs on the cable before soldering (I've forgotten too many times myself)!
There, I told you it was easy didn't I?