Thanks for this tutorial! I'm just at the point where I need to make some custom signage, and this was just the ticket.
A couple things I've noted:
Vtex.exe: you don't have to pass files through this one at a time. You can select multiple .tga's and drag/drop them all onto vtex.exe at once, and it will convert them all properly. Handy, if you're in mass production mode.
Posters not showing up in Hammer? Odds are you've mistyped a filename in one or more places. The names of the .vtf and vmt files must match exactly, and the path and file names inside the .vmt must match the files and locations exactly. And if you move the files around, you must be sure to edit the .vmt path to match the change. I know it sounds simple, but I failed to do all the above precisely right and suffered great frustration as a result.
QUESTION: When pakrating these into my .bsp, do I need to include the .vmt's, or are just the .vtf's sufficient?