custom header across multiple domains on same ip with htaccess?

I have a network of domains and sites run by a few different people. I would like to brand the sites to the network by creating a custom header/footer without having to touch any of the code on anyone's files similar to what CafePress and Bolger has done but across multiple domains. Since all the sites are on the same IP maybe .htaccess can do this for me but I do not know where to start.

 

What sort of server access do you have ?

 

Honestly I don't know what you mean by that. I have a business account on 1and1.

You can see the details and features of my hosting plan here
http://order.1and1.com/xml/order/Hosting?k_id=11043648

 

hello
no need htaccess to make this here is a simple example
create a file choosename.js
put your content in file
example :

document.write('<div style="color:#000000; border:#FF0000 solid 1px;font-family:Arial, Helvetica, sans-serif; font-size:24px">Demo</div>');

Code (markup):

now use the code bellow to display the content in others domains

<script language="javascript" src="http://www.masterdomain.com/1.js"></script>

Code (markup):

 

I do not really understand. Is there a way I can place one file in the root which contains all the folders of sites with domains which would call the header and footer across all html and php pages.

I do not want to physically edit any of the code on any of the sites, there are quite a few and more added all the time.

 

ok
mod_layout make all job for you => tangent.org download
usage
There are three types of headers and footers. You can either add a simple piece of text:
LayoutHeader "Sample header"
LayoutFooter "Sample Footer"


or you can insert entire files by using:
LayoutHeader /usr/local/apache/htdocs/header.html
LayoutFooter /usr/local/apache/htdocs/footer.html

or by URI:
LayoutHeader /header.pl
LayoutFooter /footer.php