^^ Only time the EPA would get pissed is if you were purposely venting large amounts (like your entire A/C refrigerant system) into the atmosphere. And yes, it's not a good idea, and in some places VERY illegal to do so, but if you have an accident or a leak, it's no different really. But to stay legal, it's best to have your A/C system (if it's still charged) evacuated by a shop.
To the OP: Working on an A/C system is no different than working on any other part of the car. If it's done right, it'll work right. But without previous experience, they can get a little tricky (like anything else), So here's how you can do it yourself (as I have with great success)....
My A/C compressor was shot completely. So I got on eBay and had one shipped to me for about $100 bucks from a junkyard. Installed it, and recharged it myself using those DIY recharge kits. Mine has been going strong for just over a year now. Blows very cold air, even with having a black car with black leather with a huge sunroof in the middle of summer in the desert where it's been getting up to 100 degrees each day.....and I'm not even sweating.
Now, a couple tips: If you ARE hitting your high-pressure switch and the compressor keeps cutting in and out, you need to let out a bit of refrigerant as it's overcharged. Just press the nozzle in on the A/C line above the intercooler (or the one you used to recharge the system, usually along the firewall). Let out small, short bursts until it stops cutting in and out. Some people will get all crazy if you do this (and that I'm even recommending it), claiming you are ruining the environment and so on, but like I said, it's no different than having a leak or getting in an accident where it breaks a line. Plus, most shops do this as well if they overcharge it.
Now, also to let you know, you might also have a leak, usually due to the O-Rings around the A/C lines that go into the compressor (and that's probably where the original factory refrigerant went too), AND also into the A/C condenser. $5 gets you an assortment pack of A/C SPECIFIC O-Rings which would have been better to install before you recharged the system, being that you now have it charged full of refrigerant, and evacuating that much into the air is technically illegal (and bad for the ozone, but not NEARLY as bad as the old Freon stuff). At this point, a shop would be a good idea, and they should only charge about $80 or so to evacuate your system, add in the proper refrigerant and oil to the existing A/C system. Again, I would ask them to replace the O-Rings on all the lines, and usually they do this anyway. But if you do have a leak, you probably already lost all the refrigerant you put in, and you can verify this if you reconnect the DIY charging bottle and monitor the pressure. If so, pop the lines and replace all the O-Rings. You can also look around for any greenish (like antifreeze) around the connections to see if you can pinpoint where it's leaking from.
But don't let anyone tell you that you can't DIY charge your A/C, because I have, and it works absolutely perfectly. But like I said before, it's like working on anything else and having to diagnose it. If it's broke, it's broke. You could do everything correctly with the DIY recharge, and it still doesn't work because the A/C compressor is broke, or you have a leak. Fix the problem, recharge and voila......everything works again.