The only muscle memory I’m likely to have right now are the patterns I’ve been working on, major scales and 1,3,5s.
Perfect! Gain some fluency there!
Sounds like you know where to start..
Start practicing slapping now.. it's one of those things.. that.. "the secret" can't be taught.. it can be explained to DEATH... but, just like Tremelo picking, the learner will have an "a-HA!" moment, where this ONE crucial detail in your process falls into place.
It's all in your recoil, wrist, and muting..
Check out the "My name is Mud" tab.. it's SO simple.. it's the technique that is the driving dynamic..
It IS on a 5 string.. but playing that same riff is a good "exercise" even starting on the E..
I believe that main riff part, that you'd want to learn, is only like three notes..
Just when you mute your slap..
it... it.. "KA-whEppa"s
so it sounds like more.