Well, I hate water changes too, so check out my page to see how I solved it:
Now, you don't have an unfinished room behind your tank with a utility sink like I do. But the Magdrive pumps can handle lots of "head," meaning the distance the water must be pumped up before it goes down. I love the idea of using the bathroom tub to hold the water out and drain it. Guess you could also use the bathroom tub to hold the water in too, so you can dechlorinate it. Are you sure there isn't a removable fitting on that sink faucet that is hiding the threads? The thing you see is probably just screwed onto the threads, so you can remove it?
If you can set up a holding tank somewhere, I highly recomend it. It is sweet to have heated, dechlorinated water to pump in. If a holding tank is not an option, than get a python hooked up. If the faucet really has no threads, change it! Probably cheeper to change the faucet than buy a pair of magdrive pumps.