I don't know of any decals to simulate the TPS in 1/144
scale and they would be too small to scribe on the model's surface (I'm trying to scribe them in 1/72 scale and they are still too small). As you probably already know, there are more than 30,000 of them. If you want to scribe or paint them you may want to check this web site, where
you will find drawings of top, sides and bottom of the space shuttle showing the tile pattern, these drawings are
in PDF format so you'll need the Acrobat Reader to open them.
http://spaceflight.nasa.gov/shuttle/reference/sodb/