Not sure why this hasn't been posted yet but there's a crapton of Bughunt mods spawning on the internets.
Lurkers Only/No Mercs mod/Weld doors etc
http://www.moddb.com/mods/aliens-survival-experience/downloads (http://www.moddb.com/mods/aliens-survival-experience/downloads)
Boiler added to bughunt/Weld Doors/etc
http://steamcommunity.com/sharedfiles/filedetails/?id=269584251 (http://steamcommunity.com/sharedfiles/filedetails/?id=269584251)
Adds loads to the gameplay, and Tribute finally feels a lot more like the movie without those damn Mercs. I suggest you all try them.