use segment to determine which database to use - but how ?

[eluser]cinewbie81[/eluser]
Hi,

when i type the url www.my-site.com/dell/userlisting , it said "The page you requested was not found." . This is because there's no controller class call "Dell" in my system. In my case, supposely dell isn't a class, userlisting will be the class however .. where should i set so that the system will ignore the 1st segment and treat the 2nd segment as the controller class instead of the 1st one ?