To get the dark green glow you're looking for, your best bet would be to lay a piece of vinyl inside of the dome. I would grab a couple of sheets of it from a sign company or tint place in different transparencies and see where that gets you. If you find the shade of green you like, but there just isn't enough light inside for you, I would replace the stock 39mm festoon bulb with an LED replacement bulb, just in white..
Normally for people looking for color, I'd just recommend replacing the bulb with a colored LD bulb, but you say you're looking for a DARK green, which would probably be difficult to do with an LED as they're typically rather bright.
If you do order LEDs, I personally have used SuperBrightLEDs.com and the link to the bulb you want is here:
Product Listing - CAR
The one directly above that will work as well, the only difference is that one has 4 LEDs and the one I sent you to has 6. Also, be sure to select the color of the bulb from the dropdown menu before you hit 'Check Out', as I accidentally ordered red instead of blue for my first set.
Hope that helps.