I will agree with Gary on that.. Maxim DL is worth every cent... I just shoot my LRGB data, click a few buttons and it does the rest.. dark subtraction, flat field calibration, stacking, aligning the channels and combining... I usually only combine the RGB in Maxim, as I like to do the luminance mixing in Photoshop as you have a lot more control over what happens...
Luminance is fairly easy to layer in once you've figured it out... Heres a link to Rob Gendlers guide to LRGB image processing..
http://www.robgendlerastropics.com/LRGB.html
Cheers mate... Looking good thus far, just needs a bit more work... Good luck with it mate...