Change iDisk sync location?
I don't think this is possible.
I have 5 computers linked to the same idisk. I believe that the main objective of an idisk is to make sure information is identical on all of my Macs.
For example I have found it useful to copy files from my main system to the idisk. So that information is available to my network. As I see it the idisk allows me to sync information that is not synced via .Mac. I do not believe that you can sync different information for each individual hard drive,in a system