Afghan Ops
As has been said there are several different aircraft types in civil helicopter ops in Afghanistan. Most common are MI-8's and 212's, so if it's 212 ops you're interested in you may have a chance. The two current truly civilian operators are Aerogulf (Dubai based) and, as you mentioned, CHL. Some of the operators of 212's (i.e. Dyncorp) are definitely not true "civilian operators" when it comes to Afghan ops.
In the case of CHL, the contract is brand new -- just getting going this week -- and involves 3 B212's operating under a US DOD contract. Because it's a new contract there will likely be openings as some crew find out quickly (on ther first rotation) that it's not for them. So, if I were you, I would call CHL in Vancouver and have a chat with them. If you have mountain flying experience and skills they will be much more interested in you. If you have experience in harsh environments (meaning conflict or post conflict, as opposed to weather) you'll move even higher up their list.
Calling Aerogulf in the UAE may also be worthwhile.
Good luck to you . . .
Grizz