I have to confess to a rather belated epiphany. As I was scouring scorched-on oatmeal from the bottom of a pot last month (ADHD is a handicap when cooking sticky stuff*), it occurred to me that the Zojirushi rice cooker I'd owned for 2 or 3 years has a porridge setting. Duh.
So yeah, that's how I'm making my steel-cut oats now.
ETA: *I'd set an alarm on my phone, but then left the phone in another room on its charger. Because that's just how I roll.