Tips for adding fresh coals?

I don't have a hinged cooking grate (yet) but want to try some indirect grilling. I know I need to add fresh coals every hour, already lit since I don't have lump coal right now.

Any tips for adding fresh coals quickly? There's an opening on both sides of the grate but it is smaller than what a hinnged grate offers. I could try putting them through the opening with tongs, but that seems like it would take awhile and I'd lose heat. Will I lose heat anyway whether I take 30 seconbds or 2 minutes?

Couple of ideas...
1) I have a device called a grill grate grabber. manufactured byt he Big Green Egg company, sold at BBQs Galore. It is great! (Pun intended) I can lift a grate with food on it will control and ease.
2) Fire them up in a chimney first.