I'm using my Caps-lock as "CTRL" on Mac OS X Lion 10.7.4. On Linux and Windows I can easily close and open tabs via CTRL+W and CTRL+T.
However on Mac I have to use CMD+W and CMD+T. CTRL+W and CTRL+T doesn't work.
What can I to fix this behaviour?
You can customize some shortcuts in System Preferences:
You could also use an application like Keyboard Mastro to assign control-W to a macro that emulates pressing command-W. But it might have a small additional delay or not work everywhere.
But it would be nearly impossible to have the shortcuts changed consistently or to use control instead of command as a modifier key everywhere in OS X.