Make sure your drive is less than 20gb. I would reccomend a 4 or 6gb Travelstar for the XD3 (don't need any more for that module). You don't need any software as the XD3 will automatically detect and format the drive

Your cable will be a problem. They are almost impossible to find. Before we were Ketron distributors I searched the entire planet for those cables because I did not want to buy the originals...and I could not find them anywhere. Tony managed to find a supplier for the connectors though, then all you need is the ribbon cable and a tool to make one up.

Velcro....hmmm, that would concern me in case the heat from the drive melted the glue and the whole lot moved around.

I understand not wanting to buy the whole HDD kit as its quite a few quid, but you could order just the cable from your Ketron distributor or pinch the bracket and cable from your Audya!