i agree you need to steer him, but that's all - steer him, teach him how, give him a rota - tell him say, thursday is wash day so if its not in the basket it wont get washed for a week.
but you cannot force him... if you force him too much he may subconsciously rebel when he gets his own place ...
buy him storage boxes, tubs and units etc to make things easier for him.
also include a label maker - so he can have a box of leads, a box of pens, a box of gadgets, box of figures... whatever, as well a one big 'everything' box.
maybe get him one of those basketball hoop laundry bags - so it makes putting each thing in the basket a bit of a game?
i am untidy and i don't agree that tidy house = tidy mind at all ... i think that's something neat people say to make themselves feel better.
in a way i wish my folks had tried to instill tidiness in us, i wish i was a bit tidier, but i doubt it would have worked anyway - and they weren't all that tidy themselves, our house was clean, but a bit cluttered.
they did shout at us sometimes of course - my dad got to the point of marking plates with our initials and said we could only use them!
that didn't work
but they rarely said anything about our room or about our washing etc or making beds etc.
basically if we didn't do it it didn't happen.
unfortunately it didn't make us do it much.
i remember when i was about 14 sleeping without a bed sheet for about 2 months because i couldn't be bothered to sort out a sheet! -
to be fair, i was lying on top of my thin duvet, with my thick one over the top so it was extra cosy in the winter so it didn't really matter anyway, but still ...
but i sorted it out eventually
me and my sis were untidy, but my brother was over the top neat - everything lined up, at right angles with the desk etc, no idea where he got that from - and we are all still that way today.
the irony is my folks ran 2 shops - both sold second hand stuff, and my dads was a total mess, and my mums wasn't far off, so i'd say it was kind of in my genes to be messy ... but then, look at my brother...and he actually worked in my dads shop for years!
maybe that's why he became neat... didn't like the shop...
so it just shows that nothing you do will make him be what he's not.