npc talking and dialogue

This is my first post, and when I did the search, someone already DID ask the question, but it was left unanswered because apparently someone need some facepsoer.exe file or something. I'm trying to make my own set of hl2 maps with their own storyline, and before I embark on this quest the most important thing IS the storyline, and I cant do that without dialogue. Since no one has said that its impossible, just hinted at it, I'd like someone to tell me if this is impossible, and if not, point me to a tutorial that explains how to do it.

Open hammer for hl2, find a map file called sdk_faceposer.
Compile that map then play it in hl2. it will explane all the
stuff you need to know about stuff like that then once you have played
it go back and check out the source of the map to see how they did
everything.