Installation Guide: Unzip and place the folder inside Team Fortress 2/bin/Prefab
After installing, use the entity tool, under the categories dropdown menu there should be now an option for "Item Pickup", select it and there should be the options for placing down what items in the objects dropdown menu. May need to restart hammer for it to be in effect.
Comes with White brush patches for health kits and Red brush patches for ammo packs. Skip brushes are there for stuff to be neatly grouped together.