Is there any way to set cmd + click to select a full word in textmate?
There is no easy way to do it in TextMate, since mouse events cannot be set to invoke a command. Besides, as far as I know, you cannot select text via command. So the only possibility would be to write an extension for TextMate, which is much more complex than writing snippets and commands.
However, I'm sure you can get it working system wide, because it is possible to customize the cocoa text areas (basically most applications use them, thus your changes are reflected nearly everywhere). For example, it's possible to give those text areas an vim-like behaviour with different modes. Sadly I can't find a helping link right know, maybe someone else has a good resource for adjusting cocoa text areas?