The good news is you don't need to add anything it is all in there but rather obtuse.
This is the instruction for Schematics 4. Some menu choices have changed.
- Create your trail file
- Open Files -> Options -> Define and manage commands: [Custom Command Settings...] I think that this is in a more awkward but similar location in Schematics 3.
- Select Custom Trails -> [New] and enter the information for the trail file you created.
- exit the windows.
- right click in the ribbon -> customize the ribbon
- change the Catabory to Custom Commands.
- Find your new command and move it to the ribbon area you want it in. If I remember right, earlier versions of schematics would only let you put it in a tab section that you created.
