Hi Marcel, here is the patch against linux-2.6.18-mh1 to fix 
IntelliMouse. That's the best range of changes I have time to provide: 
somewhere in these changes IntelliMouse was broken. I believe this 
happened between patch-2.6.15-mh2 and linux-2.6.18-mh1. While there are 
a lot of changes in these 17 files, but most of them are variable 
renames. I hope this helps you to narrow down the issue.

[ Does sending compressed patched works? Trying uncompressed first. ]