So...
I've got a stubborn stain along the inside of the top rim of the toilet. I have used Super Iron Out to get at it which would work fine, but I can't keep the water up to the rim for the whole 15 minutes. In fact, all of it goes down the drain. I tried stopping it up with a towel and a 4 or 5" flat stopper but the toilet drain is an odd shape. I've tried stuffing a plastic bag full of a pebbles into it even and still the water drains. How can I keep the water level up for the full 15 minutes. I have a picture of the toilet drain, but I don't have a site that I can host it from, so if you are seriously going to help me, I can send you the pic It's kind of oval shaped. Any way, any help will do. Thanks.

Have you tried using a toilet plunger. That is the one with the extra piece on the bottom that looks like an inverse cup. Also if your looking for a site to post a picture to you can post here or use a free site like picpaste.com and post the link here in the thread.

Try this.
Turn off water supply.
Flush, plunge and dip out all water from bowl.
Stuff heavy duty trash bag about 1 foot down discharge drain.
Fill trash bag with water until it blocks discharge.
Tie and seal trash bag.
Then fill bowl to rim.

Try "Cherny" elongated test plug. Just select the right size, insert it in, pump it up with bicycle pump - and it will hold water for as long as you need

Milo