I made a poster alignment tool to make it easier to import poster designs. If you have photoshop you can use this template to adjust the poster without having to jump in and out of game to see if it is aligned or not.
Just activate the colored layer to see if it collides with surroundings then once you have image positioned turn off the layer then export the image to tga format.
http://files.filefront.com/Poster_Al.../fileinfo.html