For a model-based platform:
1. Create the model in MED (easy as pie)
2. put it in your level (assuming you've already built it,

)
3. Create a new script in SED that contains this code (Lite-C)
Code:
#include <acknex.h>
#include <default.c>
action platform_rotate()
{
c_setminmax(me); //use this for a square platform
my.flags= POLYGON; //but use this if it's oddly shaped
while(1)
{
my.pan+= (whatever) * time_step;
wait(1);
}
}
void main()
{
video_mode= 8; //1024x768 resolution
video_screen= 1; //fullscreen
level_load("(level).wmb") //load our level
}
I'm sure it works, so don't worry

.
Just replace (whatever) with a number, delete either c_setminmax or my.flags= POLYGON depending on your needs, and replace (level) with your level name.
Then attach the script to the level in WED's Map Properties, attach the action "platform_rotate" to the appropriate model, and then you're good to go!
If you have A6, here's the C-Script code:
Code:
var video_mode= 8;
var video_screen= 1;
action platform_rotate
{
c_setminmax(me);
//or
my.polygon= on;
while(1)
{
my.pan+= (whatever) * time_step;
wait(1);
}
}
function main()
{
level_load("(level).wmb");
}
There's other ways with the templates, but I never use them, and I think this will be a lot more efficient than the templates.