You can simply create a button that says that for example the variable "tool" shall be 1. Then you have a movieclip with the code that says:
if the variable tool is 1 this._x (and y) is _xmouse (and ymouse).
the movieclip with the code is your tool for example a pencil.
I made a varible beucose you can have more tools and just make another movieclip and button but the varible is 2.

Hope this will help you