That sounds like an AWESOME opportunity.
I agree with the many nurses that say that you need to have your skills up to par to succeed as an ER nurse, but I don't think that's the most important thing. I think that the top... say, 3 things... that you need to have as a nurse must include (a) autonomy and the ability to think quickly and make decisions on your own -- before consulting a physician, and (b) very keen organizational and prioritizing skills. What the 3rd thing is, I'm not sure.
You can teach any person walking down the street how to insert a foley, start an IV, draw blood, etc. You can't teach any person (without a nursing curriculum, that is) how to assess and know how to start treating a patient while waiting for the ER MD to come in and see them. This is why many ED techs, a specialized name for CNAs, are trained to do much of the "tasking", and why it doesn't take a college degree to be a phlebotomist or a CNA. This is not meant to be offensive to techs or phleb's, but merely to point out that those things hopefully aren't the main focus of ER *RN* training. They're expected to be proficient, but in the first month of ED orientation, if you don't greatly improve at starting IVs/drawing blood, something's wrong!
Honestly, (again, my personal opinion), those things come with time. The more you do them, the better you get. In the ED, you do them ALL the time, every day, so you get better VERY quickly! And when you get that difficult stick, all you have to do is say so, and I bet 100% of the time you have those nurses who "everybody goes to for hard IVs" jumping at the chance to accept the challenge!
I have asked before on here, and to other nurses, whether there is some sort of "emergency nursing" or "critical care" course you can take *outside* of TNS, TNCC, ENPC, ACLS, and all the other acronyms, but haven't found any yet. I'd especially like an online course that covers the realm of emergency nursing, since I doubt anywhere near where I live will be offering something like that in the near future! But, I've found nothing. So... if I were you, I would JUMP on that -- I'm jealous! Sounds like a great learning experience and preparation for your future career as an ER RN!!!