Sorry about confusing you. I was just curious about the wacom.ko location. I checked the configure.ac and it looks like 3.7 will be the first kernel to show up in the 3.7 folder.
The headers look good for your 3.5 kernel:
And no, I was just saying I was reasonably sure I had seen folks reporting being able to build input-wacom up to and including the 3.6 kernel. Not suggesting you switch.
drwxr-xr-x 23 root root 4096 Oct 16 06:36 linux-headers-3.5.0-030500
drwxr-xr-x 7 root root 4096 Oct 16 09:21 linux-headers-3.5.0-030500-generic
In fact I wish you hadn't changed from the 3.4 to 3.5 kernel.
By the way you said you were in Precise 12.04. But it's default kernel is 3.2. So are you actually using Quantal 12.10 beta 2? I think its default kernel might be 3.4.
The other thing I'm curious about is the nomenclature of your kernel labeling. 3.5.0-030500 doesn't seem to be standard Ubuntu format, which usually only has 2 digits after the hyphen. Did you get this kernel from a PPA?
Edit: Oops not paying attention. The other headers are for 3.2 so you are in Precise, and what, 3.5 is Quantal's? Anyway my suggestion would be to boot into your latest 3.2 kernel and compile input-wacom there and see how it goes.