My parts list:
K&M 18817 Universal holder
K&M 7-232-000155 Base tube (extension for tablet holder to get it over the "2nd floor keyboard")
K&M 18954 Adapter for keyboard stand 18950 or 18953
K&M 18814 Adapter for keyboard stands Omega
K&M 19796 Tablet PC holder (small) or K&M 19791 (large)
K&M 18805 Music stand (rather mid size)
If you want, you can make this out of your keyboard stand:
Of course, you can use any solid microphone stand instead of fixing the accessory to the stand. But I wanted free space for my feet (and the foot switches).
OK, I wouldn't call this DIY, though. It's just another way.