I used to do the odd buttonhole on my "old" 290c, my first machine - four step buttonholer - think 503, but with markings for the right side, left side, top and bottom. I always felt so incapable - they would always be trapazoidal, or lopsided some other way. I found out about the buttonholers and thought why the heck don't they still do that?!?
I'm glad it worked well for you! I did an obscene number of buttonholes with the pink one and my 503 for the curtains for our gazebo. I thought it worked really well.