I've just done the exact same thing, a fishless cycle on a tank I've divided for bettas. I'll tell you exactly what I did. Firstly you need Clear or Pure Ammonia. It should be colorless and not froth up if you shake the container.
Since the ammonia most likely won't have a concentrate on it, you have to play around a bit to get the right ppm. The ammonia used when I see a lot of fishless cycling articles on line is usually a lot more concentrated than what you get at Walmart or whatever store you get it at. You want to add ammonia until you get a reading of approximately 3 ppm. For the 10 gallon tank I did, I needed almost a teaspoon full of ammonia to get 3 ppm. But it will differ depending on the concentration of ammonia you have. I started with 10 drops, let it sit for a couple hours and measured the ammonia. Then added more, and waited and checked again until I got to 3 ppm. Remember how much ammonia it took you to get your tank to 3 ppm because that's going to be what you add every day.
I think I read that you used media from another tank for this. That will help out tremendously. I took readings just about every day. Once your nitrates start to read, you cut the amount of ammonia you add every day in half. When the nitrites/nitrates have spiked after this, you do a good water change. I've done up to a 90% water change at this point. Then I add the ammonia and let the tank sit over night. Keep up with checking your nitrates/nitrites and ammonia, and once they've settled down to 0, you're cycled and ready to add your fish. I usually do a water change every day while the readings are coming down.
Make sure you skip a day after the last day you've added ammonia before you add the fish to the tank. So if you added ammonia on Monday, don't put fish in the tank until Wednesday. I've done this for 4 tanks in the last year and had tremendous success with it. All 4 tanks were cycled in 8-10 days.
If you want to see a log of my daily readings as a guide, send me a PM and I'll get them to you.