Hiding my Cable Box

Since when is a standard issue 2250 dvr not IR. I assume that's a typo.  If you want to hide it you need a RF remote like these.  But these don't have very good reviews.  Maybe there's some third party att compatible rf remote you can find (Harmony?) but that up to you to search out.  Or do as @Constructive use an IR extender as a solution.

Sorry, the installer is wrong.  There are no dvr's or receivers from att that already have remote RF control built in. They are all IR remote controlled.

You should already have an att IR remote.  It should have come with your dvr.  I don't understand why you don't understand.  Haven't you ever used a IR remote for anything before? 

IR (infrared) is a form of light.  You just can't see it.   As such you can't "shine" it through objects any more you could shine a flashlight.   So no, you cannot put the dvr behind anything.  One way or another dvr has to "see" the remote's IR ("light") signal.  Period.  That's it.  Nothing else*.

Your only alternative to an IR remote is an RF (radio frequency) remote which can send radio signals to a device that can receive those radio signals and in turn control the dvr.

I hope you understand IR remotes at this point because I don't know how to make this any more simple.  Maybe someone else posting here can if this explanation is not clear (or good) enough.

* IR extender's can be used to remotely send the IR signal to a device the emits the IR remotely.  I put this here because this only complicates the basic description.  If you must hide the dvr then consider these or the RF remote (which is basically the same thing).