Pair trading is very simple. I have developed my own pair trading system website. You can also use excel. Though pair trading is easy you must make sure you choose the right stocks. I remember a trade where I lost a lot by pairing GAIL and ONGC. Historically the pair produced great backtest results but that day due to some oil pricing announcements the prices went wild. But these could have happened for straight traders also. While pair trading is always good to use some options for protection.
You can post your doubts on pair trading.