change prim size and retain esisting prim

I have a cube with a hollow - I want to leave all the settings (tapers etc), key and textures of the prim untouched, yet change the size of it by a script.

I use Prim_Size, but the hollow dissapears? I realize that I can use Prim_Parameters , brim_type etc but doesn't this createed a new prim and delete the old?

I guess what I am trying to avoid is to having to reload partially loaded textures.

Maybe I do not read what you mean to say, but I see no problem in using llSetScale(vector scale). It will not change any other attributes but the size.
It will not work for physical prims though, see:
http://www.lslwiki.net/lslwiki/wakka.php?wakka=llSetScale

Nope.

Try putting llOwnerSay((string)llGetKey()); in each time you do llSetPrimitiveParameters -- you should find it stays the same.

Both llSetPrimitiveParams([PRIM_SIZE,<Vector Scale>]);
and llSetScale(<Vector Scale>;work without changing anything but the size, what exactly is the problem you are having??

Thanks evryone - especially Taff for sending me an example