well, for barrels, I use following code:

action barrel
{
my.shadow=off;
phent_settype(my,ph_rigid,ph_box);
phent_setmass(my,20,ph_cylinder);
phent_setfriction(my,20);
phent_setdamping(my,50,50);
phent_setelasticity(my,30,30);
}

you may have to adjust that, I turned the shadow off because I had hundreds of barrels, and each barrel casting a shadow would not be so good for the framerate.

I guess that I dont have to mention that you have to assign the action to an entity, and include the script if you put those lines of code into a new script

So, enjoy