This mod is a Half Life 2, Episode one, Episode Two and Synergy mod. There is a readme on how to install the mod (based on Windows 7 64bit). It is not 100% perfect but it does work, so I'd say 90%, the turret is friendly to nearly all the friendly npc's, I'm still testing and find that the turrets won't attack alyx when she follows but when shes not is does attack her as if her npc code has change.
A few pictures of me playing on HL2 Episode 2 with upwards of 25 turrets protecting the Vortigaunt and Alyx.