ArcMap grid, convert to local coordinate system

Hi,

I have what seems like should be a very simple task. I am trying to make a location map which is composed of a variety of aerial images, elevation grids, and shapefiles and have a map grid indicating northing/easting. I would like to convert the map grid to a local coordinate system, which only involves subtracting the x and y of the origin point (which is located in my map extent).

There has got to be a simple way to subtract a fixed number from the map grid (i.e. make a "false grid") to display it in the local coordinate system. I realize I could project everything into a custom coordinate system, but this seems like obscene overkill just to subtract one number from each x and one number from each y.

Any suggestions?

Thanks