I'm buying a Pioneer DEH-1300MP CD/MP3 Receiver to replace the factory one in my 2000 Honda Civic LX. The Pioneer's dimensions are 8.9 x 10 x 4.4 inches.

It'll fit, but where do I get a faceplate or something to hold it in?

 

Looks like a single din unit. Should bolt right in, two bolts on either side. You'll have to remove the whole console to get it secured though. There are a couple of DIY's in the DIY section for this.

 

the 2000 civic is a factory douple din opening, you remove the radio and pocket and install a dash kit available from metra, scosche, best kits, or american international.