Did a quick peek at the inventory class. Apart from doing the nescesary xml edits in windows/xui.xml for changing the number of toolbelt slots, it looks like you have to edit the dll (or DMT it) in 2 places too.
inventory class: up the array dimension to your wished for number of slots + 1 (protected ItemInventoryData[] slots = new ItemInventoryData[9]; )
in IL code change the ldc.i4.s to your value
And there is some hardcoded value in the CanStackNoEmpty bool (for (int i = 0; i < 8; i++) )
in IL code change the ldc.i4.8 to ldc.i4.s and put the toolbelt number of slots (not + 1 here) in as operand
As said, a quick peek. But this should give you a direction
Cheers
-edit- there are also 5 hardcoded 8-slots in XUiC_Toolbelt class. Those would need attention too.
You guys are speaking Japanese voodoo. I have NO idea how to accomplish that. (Sorry for the incredibly slow reply, life you know?) I'd be happy to test it, but without some instructions written in crayon, I'm going to blow something up.