You will need to find the valve cap ( slightly larger than that of a tire valve cap ) There is a lowside cap and a high side cap. The valve under the caps are different sizes so you will only be able to connect to the correct one, this is the low side cap. It is located between the compressor( some times on the compressor ) and the evaporator( located at the firewall ). This procedure should be done by a qualified technician as the chemicals are under extreme pressure adn can cause harm.
Reference Link : http://www.freeautomechanic.com/airconditioning.html
It is located between the compressor( some times on the compressor ) and the evaporator( located at the firewall ). This is as exact as I can get. You will not need to take anything off to get to it. And you should be able to see it with the hood up if you spend a minute looking. It is a cap usually black ( if it is located on compressor it should be green ) . The cap is about as big around as a marker and 1/2 inch tall.
No problem at all. According to Mitchell repair manual the valve are on top of the compressor. The compressor is belt driven and a clutch that is mounted on the front of the compressor is what is being turned by the belt. There is a manifold that bolts to the top of the compressor and this is where the valve are according to the manual. You should be able to see the valves and need to remove the valve cap ( if it isn't missing ) then connect you hose.
Picture of the compressor assembly :
The silver tip in the middle is an example of what the valve looks like without a cap on it.
Best picture I could come up with :