How do I write htaccess file for my codeigniter setups

[eluser]Unknown[/eluser]
hello everyone ,
I had a codeigniter setup on my server and it is v1.7 ,now i have installed my new codeigniter on same server problem is if i access www.mydomain.com it is the old codeigniter and the new folder is inside this setup so ideally www.mydomain.com/new should take me to this new codeigniter setup , but as the codeigniter works it searchs for controller named "new" and show 4040 error( also to inform I have routed my requests by removing my index.php so as to make links user friendly) , I tried all code given on net still cannot find any solution any help would be appreciated .

Sorry ,If I am asking this question out of the regular posts.