ex: make an entity, let's say event 101 no flags what's so ever.. say you want to appear it in a worse possible places to be in, make an entity event, lets say 201 with flags 2000(pc press down i think, going to check it later) then write a script
when you press down on entity 201, entity 101 will change into entity type 149, a horizontal moving block.
<CNP is change npc, <ANP is animate npc.. but I think you already know this...
My hell mod is chunk full of this <CNP and also <CMP
you might want to make a testing rooms