Well what I do is just stop by the pet store and pick it up. Talk to the person there and ask what they suggest for either round or tape worm which are the 2 most common. Both should come in capsuls if not chop them up mash them what ever and mix it in with their food. If they refuse it just dont offer any ther food and maybe keep them indoors since they can always find mice outdoors to eat instead. Sooner or later they will eat it. My mom has a very finicky cat she had to withhold the food until around dinner time then mix it in with tuna. YOu could force feed them but to me thats just a pain and unnecessary.
Its pretty simple and usually does the job within 24 hours.
If youre happy and ya know it slap your face!