Salt, rub them down with salt leave it on them for roughly 15min continue to rub it into their fur during this time. Then give them a bath and rub their fur vigorously with 2 lemon halves. this will kill the fleas. I just did it to a rescue this weekend and it took care of all the fleas.
Bathing a cat is not easy, try putting shampoo in the toilet and put the cat in and then flush.. hahaha, just kidding. Just leave the salt on it and rub it with the lemon that's what kills the fleas, the bath is just to remove the dead ones.
dont own one