Ignore Regex negative lookahead?

[Bill Barry]

I am trying to get hg to ignore everything except a couple of folders 
within a directory (two folders actually), but the only way I can think 
of to do so would be to use a negative lookahead regex:

Containers/(?!DNN-(Blue|Gray))

That should pass for everything in the Containers folder except for the 
two folders "DNN-Blue" and "DNN-Gray" (which I need committed). Except 
that it doesn't (negative lookaheads don't seem to be supported in the 
regexp ignore syntax). Is there anything I can do (or do I have the 
expression wrong? I have never written Python regexes, but I assume they 
are pretty much the same as the Perl ones that I have some experience with)?