[Typo3] load file setup.txt into TS setup

[Elias Humbolt]

Is there a way to load an external file setup.txt into TS setup? I want to 
take the setup.txt from css_styled_content change some things and then 
replace the setup that comes with css_styled_content with my own file.

I know I could just copy the stuff into TS setup of my template but I would 
prefere to have an external file, because I intend to use it in more than one 
setup.

How about creating an extension that does not contain anything but this setup 
file? Is this a good way to go?

If so, how can I make sure, the values in my setup.txt override the ones of 
css_styled_content?

-- 
elias