1) Go into component mode and pick all of the poly facets that you want to split off of the original polyset.
2) Polygons > Facets > Extract
3) Polygons > Separate

This will create a group node that contains each individual poly. You can then select all of those polys as objects and make them active rigid bodies and then throw some forces on them. There is a problem though : Each poly is touching the one next to it, and you therefor get alot of interpenetration errors. Here's a couple of ways to get arround this:

Method 1. This method is quite slow because all of the polys will be able to collide with each other.

Select all of the individual poly objects in object mode
Modify > Center Pivot
Scale .9 .9 .9
Create active rigid body with standin shape CUBE
Add a field of some sort

Method 2. This method is faster because it puts each poly on its own collision layer. This means that the polys will pass through each other and will not collide with anything else, like the ground. You can still put forces on the polys.

Select all of the individual poly objects in object mode

Enter the following MEL command:

$polyObject = `ls -sl`;
$numberOfPolys = `size $polyObject`;
for ($i = 0;$i < $numberOfPolys;++$i){
rigidBody -active -c $i -sio Cube $polyObject[$i];
}

Add a force