In ResEdit, make a new file and save it, calling it something ending in ".rsrc". Make a new resource (choose "Make a New Resource" from the Resources menu). Choose type "crsr", which is a color cursor.
Make as many cursors as you'd like there. Each one will be assigned an ID, or a number. Write this number down someplace. In a blank file, the numbers normally start with 128.
When you're finished with your artistic endeavor, save the file and close it. You must close the file or else Indie won't be able to open it.
To set a cursor, use a trigger. Make a trigger and attach it to any old event you happen to like (like a button click, for instance). Make a new model-action of type "Set Cursor Model Action". Now type in the ID of your crsr resource (remember that random little number?).
If you want a normal cursor back, you can do "Reset Cursor" model action. If you don't want to have to find the button that resets it, but are tired of using your gas sampler as your text editor, you can type (cursors:reset-cursor) into the Messages window.
Warning! Screwing around with cursors is the most likely way you can totally hose Indie and make it all blow up. Though I do as much error-checking as I can, if you make a bad res file, bad karma could easily go down. Save early and often.