I'm using the drylok method. Just have to wait for things to dry. I'll probably rinse it before I put in the tank. Once in the tank I'm going to keep an eye on the pH but the beauty of the drylok method is that it shouldn't change the pH much if at all.
Here is a showcase of DIY backgrounds on the cichlid-forum. Malawi_Junkie and mightyevil are two users that use the drylok method.