BTT Snapping with another mouse button

I'm on macOS 13 Ventura (may not matter), but a lil feature from M$ PowerToys I really like for window management is showing & hiding drop zones if another mouse button is held down. Like, start dragging window with left button, hold right button, and areas appear, but go away when you let go. I can't figure out how to get BTT to map any other mouse buttons to Shift only while left button is held down (Shift is what I use to show BTT snap areas). One-handed window management is NICE.