I don't know of a way to do that without disabling the application switcher altogether, but there are ways around switching to one specific application.
Pressing command-tab switches apps in the order they appear under the application menu in the upper right hand corner of the screen. Pressing command-shift-tab will do this in reverse order.
Or you can just select the menu and drag out an application window (don't know what they call it) so you can switch applications by clicking on the one you want.
But I prefer to use a freeware control panel called LiteSwitch
, which lets you select what application to switch to.