For the most part what davehk said is true except for the remark about requiring a neutral(?).
However, there are some new screw in style replacement fluorescent lights that are dimable.

So, if it's a built in fixture using standard 'tubes' then you will need an appliance module.

Also sometimes using a dimable fluorescent light with a lamp module will cause the lamp to come back on after it's been turned off. If this happens then the only solution is to open up the lamp module and disable 'local control' by cutting a track on the printed curcuit board.

If you have any more questions please feel free to ask.

O