The IFT supplies them this data (the SCT has not had any involvement with broadcasting stations in a number of years). But only the 2014 versions (and earlier) show transmitter sites (the more recent versions are better Longley-Rice maps though), and the way they're drawn makes them hard to find and requires you to have a map of electoral sections on hand to compare.
Also, they show XHLTN off near the coast somewhere and XHMORE at the Cadena studios. Which makes far more sense than XHLTN being there. I suspect XHLTN may be on Mt. San Antonio as Imagen TV's transmitter is apparently there as well.