Here is what I copied from a post about this a long ago.
So there are a couple of different CIDR protocols out there. Some people swear by theirs more than others. This is the protocol we use, and have had a lot of success using. It is one of the more commonly adopted protocols.
Day 1, We give a shot of 2 cc's of GnRH (you will hear this referred to as GnRH or possibly Gonadotropin, the GnRH drug we use is Cystorelin). Also on day 1 insert a CIDR into the vagina of the animal using a CIDR insertion gun. Here is a good video on the process of inserting a CIDR.
http://dotsub.com/view/d970121a-6d78-4c34-b7bb-50872b6fc748
On Day 7 we pull the CIDR and give a 5 cc shot of Lutylase (this is the drug that is referred to as PGF2a or PGF2 alpha) Lutylase is probably the most common PGF2a used. After pulling the CIDR and giving the shot of Lutylase, you should have heat withing 48 - 60 hours. In my experience heifers usually happen earlier than cows. If you see standing heat, breed off of your normal rules behind standing heat. If you do not see standing heat breed the animal at 72 hours post CIDR. (This has changed since I originally posted it. We have been going with 60 hours on cows and 56 hours on heifers). We usually give a 2nd shot of 2 ccs of Cystorelin at this time. I have had a lot of success breeding off of timed AI like this where you never see standing heat at all.
As far as how it works the reproductive piece behind it is this, and skip this paragraph if you don't care. You give the first shot of GnRH on day 1 which clears the dominant follicle from the ovary. This is the point where you essentially start from scratch with the animal. You insert the CIDR which is progesterone. In a normal estrus cycle Progesterone levels spikes rises and then right before estrus it falls off dramatically. With the CIDR you spike the progesterone level and create a new 7 day corpus luteum. You pull the CIDR which drops the progesterone level, and give the PGF2a which causes your 7 days corpus luteum to regress. Estrus should occur at this point. You breed the way of the standing heat. As I said you don't have to give the 2nd shot of GnRH, however we do. Without giving GnRH you could possibly have a persistent follicle on the ovary where the cow is continually coming into heat every 7-10 days.
The CIDR protocol above works fantastic for me. I use it to be able to breed cows on the weekend (I work during the week). It also allows for a tighter breeding window.
There is other protocol where you can bring animals into heat quicker using just Lutylase, but it is not as reliable as the CIDR + Lutylase method.
Hope that helps.