I have an "05" Civic with a P1456 code. I have researched and know what the code is.

(1) Even though this thread is old would this list still be accurate for an "05"?
http://honda-tech.com/showthread.php?t=466877

(2) Would this procedure work for an 05 if you don't have a scanner? What color wires would the 05 have?
http://www.honda-tech.com/showthread.php?t=1901557

(3) How do I reset the CEL in a 05 without pulling the negative cable if I don't have a scanner?

 

The jumper wire method of retrieving CEL codes does not work for 01-05 Civics. You can clear CEL codes by removing the 15A ECU/ECM fuse #6 under the hood for a few minutes.

Regarding P1456, have you checked whether the gas cap is loose or the gas cap seal is broken?

 

Yep I checked the gas cap, it looks good. I also took it out today and listened for pressure in the tank. When I opened up the cap I could hear pressure coming from the tank.