In Delia Smith's Summer Collection (BBC Boooks) there's a recipe on page 59 for Thai Red Curry Paste. If you substituted the red chillies for green chillies, it would approximate it even though it might not be authentic.
Each time i make this it is different depending on what i have in the cupboards, but basically for four people i would use the following: Half or one deseeded chilli, 1 bunch of coriander, a couple of teaspoons of limegrass paste, 2 or 3 cloves of garlic, and a desert spoon of soy sauce.
Green paste:
coriander, garlic, lemon grass, lime leaves, fish paste, green chillies, tsp ground coriander and cumin, galangal or ginger, veg oil
whizz it all up - then stir-fry with chicken or meat. add some cocnut milk and some fish sauce or salt..
and bob's your uncle!
Red paste similar, but add basil instead of coriander and paprika as well as the other spices, and red chillies instead of green.