How hard is it to litter train a kitten?
If they are so small you can hold them in your hand then lock them up at night in a carrier large enough for them and a cat box. Little kittens have a ( i have to go dance ) when they do it put them in their box. They also get so busy playing they don’t make the box so have a emergency box in each room they are in until they are big enough to have bowel control. If they are bigger say two pounds then feed them next to the box so they know where it is. Use clay litter so the strong smell of fancy litter doesn’t put them Two cats two boxes.If you live in a town that has a spay neuter clinic call them. Ours does as young as 4 weeks. Yes he is an amazing surgeon.
They are very easy to train. Bring them in and show them where the litter box is. Use your hand or something to move around the litter like they do when they cover up their waste. They catch on very quickly. The fact that the landlord does not allow pets is another problem. Don’t leave them out during the day unless you want the landlord to take them to the sheler.