Not sure there is an attachment that would work with the Mitchell gripping station, but really should not need one. If you can put the club in a vice, or in that gripping station with the leading edge of the clubface vertically square, that is really all you need to do, and then do a visual check once you remove the club from the vice or grip station. Most grips will have dots or lines on the mouth end and the but end you can use as visual ques that the grip is on straight. Probably would be relatively easy to set up some kind of vertical reference line to use while the club is in the clamp, even if it’s just a straight vertical line on a wall.
Britt Lindsey