Welcome to the Seven Forums
What are you using to edit the theme?
I use Windows Style Builder Ave's Windows7 Style Builder
to edit themes and all them text colors can be edited with it.
If you purchase it I can help you find them locations.
The only other way would be to contact the theme maker and asked them to change the text colors for you it's not cool to change somebody else's work and then distribute it but you can do it for your own use.
Let me know if I can help.