This topic has been discussed many times, and no good solution has ever been found as far as I know. A couple of days ago Captain America asked me about this again (for a mod he is working on) and I only remember theorizing about this topic a couple of months ago, never actually testing stuff. Today I did, and what do you know... I actually found a working fix! The solution is near to what I described back then, just a little different. A very cool workaround that may prove usefull in other scenario's as well...
Here's a small in-game movie for ya:
http://sh4.skwas.net/media/props.wmv (8 MB, 30s)
Ok, here's a video walkthrough describing how it is done...
http://sh4.skwas.net/media/props_tutorial2.wmv (43 MB, 9m10s)
If you decide to use this method, please credit me
Oh and one more thing, pardon my english pronounciation :rotfl:
[edit] For future reference, here's the first mod that uses this method:
http://www.subsim.com/radioroom/showthread.php?t=138374