Well, take a first guess you'll probobly get it, just lewer the pretty marines to beside (or near) the tripmine, ht it with your Fade's acid rocket or Bile Bomb if use have it, i'll blow and kill of any marines that are pretty near to it. Unless they are HA, but it isn't that hard aswell, most of them put more then 3 to keep out the skulks, so you just hit one, then all usually go, and that'll take out a HA.
I just want to show a little example on what a nice tripmine hit can do when it's laying on a ground, near a Armory (silly mawines twipminds are for the smart ones :o)

They built 4 tripmines around the armory and i saw a pack of marines getting their ammo... Know it's not really indepth, (how can it, just shoot it, when they're near, you can even hit the laser part if you want it'll trigger it, and blow up!)
Oh also, i forgot to mention, jumping thru the laser part and not getting hurt