I think it is a pretty patient cat if he has to put his behind into a box that he can't really fit into, to pee. If I were the cat, I'd go pee in the owner's shoes to protest the arrangement. Is the cat spayed or neutered?
Your friend should go get a plastic storage bin, the kind they sell to put Halloween or Christmas decorations in, they're about 2' high by 3' by maybe 15 inches. He should set the lid aside (the box will be left open topped for this arrangement), and then sit the box on the floor in the regular way (on its base as if to put something into it) and cut a door out of one of the (narrow) ends from the top lip to about five inches from the floor, so kitty gets the drift that this is the catbox. These boxes are a lot cheaper than catboxes, and handier, and bigger too, and they are plastic so they don't leak and can be hosed out and cleaned every now and then with soapy water.
Your friend should invest in some clumping litter, but not the scented kind, (there is a kind made of wheat leavings that is really good). He should put an entire sack of the non-scented litter in the box, and be prepared to scoop as kitty uses the box. If kitty is spraying, he won't be able to elevate his bottom high enough to get the urine over the top of the back of the box, since the box is so tall. And the owner will know that is what the cat is doing by where the spray hits.
Cats like a lot of litter and they like it clean. If your friend is not scooping the box regularly, he should.
If he can't be bothered to do any of this, he might think about re-homing the cat.