At an absolute minimum, assuming your Icom can cover 137MHz FM, you don't need anything except software to decode the signals. There is lots around, I am using WXtoImg because it offers lots of very nice enhancements on the paid-up version (cost about Ł30) and the demo version seemed to do a better job than all the others I tried. JVCcomm can in theory do it, it has the advantage that it gets data off the Pactor, but it did not work well with the weak and dirty signals and cannot do the very clever things such as shift frequency to allow for Doppler shift.

You just connect an audio output from the radio into the sound of your PC, tune your radio to the frequency of the next satellite and wait for it to come over. WXtoImg will predict this for you. On the paid version it will tune the radio for you too.

BUT. The big but is that the results with a standard VHF aerial will always be mediocre at best. So the 1st enhancement is a better antenna. I plan to make one out of a few bits of wire and drainpipes following these instructions. I will report back.

If you want to go the whole hog, get the R2FX APT Receiver from here. That should give superb results with a decent antenna.