G2V calibration for RGB images

[Ivor]

Having played around with my mono camera I've taken a number LRGB subs and when I staked the images I quickly realised I need to something extra to balance the colour and a little googling pointed me to calibration with a G2V star. I've duly collect a bundle of RGB subs and stacked them and I now need to calculate the total flux value or ADU ( Astronomical Distance Unit?) for each sub stack. I understand the normalisation bit but I'm stuck on how to calculate the Flux/ADU value, all the articles I've found use either Maxim or AIP4WIN neither of which I have.

Does anyone know a way of doing this without spending anymore money (or at least very little)?

I have the following applications at my disposal:

Photoshop CS5
Nebulosity
CCDSOFT V5
CCDSHARP
CCDOPS

Thanks