You can then Right click > Add to panel > window list
I just booted Mint7 live CD to try this out.
It works, but you have to be careful where
on the empty panel you click. R-clicking to the left end doesn't give the "Add to panel" menu option. R-clicking to the right hand end does.
So you'll have to experiment until you find the menu option.
Me? I'm back with KDE3.5