Bulk changing GeoTIFF raster position

[danh_dfo]

I am working on a project where I have a large number of GeoTIFFs. By default, they show up at the "User images" raster data position. I would like to move them all to the "Route shields" position. I've tried editing the actual project file. I have managed to get the GeoTIFFs to only show at zoom level 17 or better, but every time I try to make changes to the "Raster.DatPosString" entry, XMap responds with a corrupt file. Is there any easy way to make a bulk change like this? I have about 750 entries, so I'm not looking forward to doing it by hand.

Thanks

Dan

[tcovill]

What is the coordinate system that the Geotiffs are in?

[danh_dfo]

I believe it's NAD27 and Zone 11.