I love M105 and use it for this area as well as a bunch of other areas. You'll find that you will use M105 for a wide variety of polishing applications and to me it's well worth the money.
My regular method for this particular areais to use a fairly substantial wooden paint stick, mf towel and mix a "cocktail" of an abrasive polish (M105) with a finish polish (
1Z Metallic Polish or
P21 GEPC). Seems kind of harsh but it works good for the really hacked up scratches behind some door handles. I then go back over it with a less abrasive polish to brighten and shine to match the surrounding paint. I've also used those foam finger thingies for this.
The problem is you can get behind the door handle too good and the paint stick works the polish on the MF behind that area well.
There are plenty of "rubbed out by hand" sections on every vehicle but this is one of the most difficult areas to access. Great question!