Upside-Downer Sleeve Increase Help!?

[AliceV]

A dozen years ago I knit an upside-down sweater--I'm wearing it right now. I want to knit another. The sweater is knit in one piece from the collar down, and I can't remember how I did the increasing for the sleeves. The pattern says to mark stitches, then on knit rows to M1 before and after those stitches. However, I remember doing something different so that I have a really neat sort of 'ridge' two stitches wide at the front and back of each armhole. My mother taught me how to do it then, but she has since passed away. I have looked at the M1L and M1R videos and tried various combinations on a sample, but nothing looks quite the same. Any ideas for me? Thanks so much!
Alice