snapnames rules at .com for now If the name is not so popular another service like service like pool can work too
First its 'backorder' not 'backdoor' And for playing safe you need to backorder at least on 3 services. pool/godaddy/snapnames
Just go to pool.com (or other site that provide domain backorder) and create account, add your domain and wait untill it become free, when nobody except you want to register this domain else, then you will get it. Otherwise, there will be bidding, who gives more, will win the domain.
Never mind, but all this is actually waste of time and money. There were the days when all this was possible but no more. Google is now a registrar and they check the domain registrant history and accordingly give PR and rankings.
Amazing, people are still running after the PR domains unaware of that when they want to achieve is not gonna happen. Why people want everything ready made. Why not put some efforts, build your own website, work hard and see the results. They will be much sweeter.