So, I know the hyperbass has an output for each string, but what sort of output? Are there just four 1/4" jacks on it, or is there some special DIN cable that has four leads or...?

I ask because I'm having a custom pickup made based on a Wal pickup, and it will have the capability for separate output of each string. This would be cool, but not worth having 4 cables coming out of the bass, so I'm wondering what the alternatives are. Thanks!

I'm not sure if this will actually answer your question, I don't think it will, but here ya go:

The middle two strings are not used for “Adhan”. Since the Hyperbass has separate magnetic pickup outputs for each string, Michael didn’t even bother connecting the outputs for the middle two strings to the mixer when recording "Adhan".

taken from his tunings page

I read somewhere that he uses a special cable for this. Not sure on the specifics though sorry.

Can't answer the specific question, but at the very least you would use two stereo TRS plugs rather than four separate mono plugs. It wouldn't make any sense to use mono jacks when, for the same rpice and half the size, you could use two stereo jacks.

Well, I found the answer:

http://www.talkbass.com/forum/showpost.php?p=1690130&postcount=12

and a picture:

http://www.talkbass.com/forum/attachment.php?attachmentid=11157&d=1101603026