Try the catnip on the scratching post idea that has been posted here -
to get them to switch from the carpet and use the scratching post
instead.

Also, something I've seen suggested (but never used myself) is the
watergun theory.   keep a water gun handy and when you see them
scratching on the carpet then squirt w/ water.  

They also make a spray that is supposed to deter the cats from
scratching - get that and try to spray that on the areas they are
pulling up.

As for the urinating - please have them checked for UTI problems.
Then some tips here are 1.  clean the area very well w/ a enzymatic
cleaner (natures Miracle if you are in the US, or a enzymatic laundry
soap if you are in the UK).  
2.  Clean again  :-)
3.  Cover the area w/ furniture, or tinfoil or tinfoil w/ balled up
masking tape on it.
4.  If they continue, place a small bowl of dry cat food on each spot.
Cats won't urine where they eat - they are too clean for that.

Finally, I'd suggests that you get multiple litter pans and place in
different areas.   2 cats need 2 litter pans, maybe even 3 litter
pans.   Clean often.   Try to make sure the litter pan is in an out of
the way place (give your babies privacy to go potty).