How do you dry hop in your keg? Thats my one enemy with IPA's is that time really isn't on my side. Do you use whole or pellet hops, in a hop bag I'm assuming?
You can use either whole or pellets! For whole, you can use a bag or one (or more!) of those "tea balls"- the large ones that you'd use to make tea with loose tea leaves. You can only put about 1/2 ounce in the tea ball, so you may need more than one. Make sure it's stainless!
For pellet hops, you need a tightly woven hops bag. Like this: http://www.austinhomebrew.com/product_info.php?products_id=1054 You can use that for leaf hops, too, of course!
I dryhop in the keg often. Since it's cold, I don't get "grassy" flavors but I do get nice hops aroma and flavor.