First, and basic question is there other alternatives? Say fuck it, and move on. Really ask yourself if its worth Your Time, Effort, and Resources to fix him.
Seriously you have important shit to do he doesn't.
If it is, or you want practice changing people.
Operant conditioning, and psychological manipulation.
Starting off tame. This takes a while.
Ask the NEET to do something for you. Make sure it's Easy, and Simple. Doesn't matter what.>He does the thing. He'll be more willing to do another thing that is roughly as easy, and simple.
Doing that over time makes the NEET willing to do anything for you.
Additionally, you can add 'punishments' and or rewards
when he fails to do so. It shouldn't be connected to you. Just a random 'act of god'.Finding out what he likes, and dislikes, and what he absolutely hates will help with all endeavors going forward.
'Randomly' switching tv. As a minor punishment. It can switch channels, turn off, switch to an alternate source (if applicable), turned mute, ect.
Easy to do with a universal remote. Minimal cost put in.
Minor things that make his life harder. Reverting it when he doesn't fuck up. Salt shaker is filled with sugar, or flour, or an alternative substance. (Might have the reverse effect due to him eating takeout.)
Toilet paper is replaced by a prank roll.
If you know his email sign him up for all the junk mail.
Rumors are a bitch to deal with. Find a gossipy woman have either you, or the old woman start a minor complaint. They last for a very long time sometimes with unexpected results. Use at your own risk.>>1521>>1522
Cutting the power is nice, and handy.
If you own the wifi change the 'parental settings' have it turn off access at certain times ect.
Itching powder.>>1522>>1523 Just read that after I typed this part up.
Him asking you for a quote means that your mom makes a decent check off of the sob. Make sure you have someone to validate, and verify the contract. Legal resources as a third party witness are available. That helps if the fucker tries to worm his way around paying for services. Also protects your mom's cleaning company from retaliation attacks.
Suggest to him that a cleaning service for your mom's cleaning company for a daily maintenance. Further money for her. The house is clean, and he has to work to pay the bills. (Not including him raising rent)
This also applies to psychiatric care as well.
'Prank' videos are a resource on just about illegal, but it's kinda grey. They aren't funny, but as a means of strange, and unusual punishment they work just fine. (I don't recommend doing that)
If you have a contract read through it carefully, and see if he is failing in any of his responsibilities. See if you are entitled to compensation or further legal action. (Down side you may be out of a place to live.) If you have the money, or the connections you can lawyer up. (It EATS you Almost All Your Time)