Dale,
I found this link in this Forum using the search function. I like it because many of the colors are matched to their Methuen numbers.
http://www.mossie.me.uk/ww1/xml/colours_list.xml
You might also look at
World War 1 Colors
Me? I've never used them, but I'm about ready to just buy the misterkit paints shown on the link you posted, since they've done all the hard work of researching the colors.
Greg