I need to change the water pump on my 99 Bettle (2.0 L)
I dont have the special T10020 tool for adjusting the tension pulley for the timing belt. Can I change the pump with out adjusting the tension?

If so, how do I get the belt off and back on?

you really do need to use the tool. You can just unbolt the tensioner to get the belt off, but then youll play hell getting it back on with the right tension and all. go to a VW dealership and the peeps in the parts department can get you the tool.