Can you play half life source on garrys mod

Well, in the steams list of games which you can use on garrys mod it dosent show Half life Source. But if you type in gman squad on youtube you can see their playing the storyline on Half life Source. I asked them the same question and they said yes, you can play the storyline if you have garrys mod and Half Life Source. I dont know for sure because i have not yet tried it.