The script is simply:
default{ state_entry() { llVolumeDetect(TRUE); } collision_start(integer total_number) { llInstantMessage(llDetectedKey(0),"<enter message>"); } collision_end(integer total_number) { llInstantMessage(llDetectedKey(0),"<leaving message>"); } }
On a phantom prim around the entire building. If I sit on anything and then stand, I get "<enter message>". Seeing as "<leaving message>" isn't being triggered, I'll try storing a list.