Open project and start VBA
In Global.MPT insert a new module and put your code in that module.
Back in Project RightMouseButton on a blank toolbar space and click on Customize...
In the popup:
1. On the Toolbar tab create a new toolbar or select an existing one.
2a. On the Commands tab, under Categories, click on All Macros.
2b. On the Commands tab, under Commands, drag the macro you want to the toolbar you selected in step 1.
2c. On the Commands tab you should see a button called "Modify Selection" ... make any changes you want.
3. Click OK to close the popup
Depending on your environment you may have to:
4. Click Tools | Organizer to move the toolbar and the module from your project to Global.mpt (or, perhaps, it's the other way round).
5. Save the project and update Global.mpt
The next time you open the project you should see the toolbar and the button.
I think I've got the steps right. Play around a bit and see what happens.
(BTW, you don't have to doublepost. Most people providing answers here read all threads flagged with a "new message" icon.)