It's a lot less complicated than you think, you don't need to worry about textures or anything like that:
1. Create a single plane the size you want it to be (make sure it's upright and your origin point is the bottom middle of the plane)
2. Add a plain material to it
2. Unwrap to bounds (basically unwrap it so that the four corners of the plane are at the four corners of the UV map)
3. Export it to .x
Then all you need to do is create a folder with the .x in, add any image you want shown, plus a .bmp (64x64 in 24bit bmp) and an .fpe file (easy way to do that is copy another one and rename it), change the details in the .fpe and done.
Here's an example:
See files attached.
List of files: Poster.BMP, Poster.X, Poster.FPE, movieposter.PNG
Contents of the FPE file:
;header
desc = Poster
;visualinfo
textured = movieposter.png
effect = effectbank\reloaded\entity_basic.fx
castshadow = 0
;orientation
model = Poster.x
offx = 0
offy = 0
offz = 0
rotx = 0
roty = 0
rotz = 0
defaultstatic = 1
materialindex = 2
collisionmode = 0
;statistics
strength = 25
explodable = 0
;ai
aimain = default.lua
I'm at work so can't use GameGuru to poster a picture of it in the editor, but here's a picture of it in entity workshop which should give you an idea.
Now you don't even need to make any more models for different posters (unless you want to change the size and shape of the poster), to use different images simply copy the bmp and rename it, then copy the fpe, rename and edit, then drop in another picture, it will fit to the size of the model.
When i get time i'll try to do a quick video on how it was made if that helps.
(note the image used in the poster example was taken from google images, and although it was listed under usage with edits, it's probably best if you don't add it to any commercial publications).
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