How can I create a custom syntax highlighting brush for Linux command line examples in WordPress?

I write a lot of how-tos and tutorials on my blog (self-hosted WordPress) and I’d like to be able to create two custom syntax highlighting brushes for posts that include stuff typed into the Linux command line — one brush for standard user commands and another for root commands.

Currently, I just use <pre class=”brush:shell”>, but I’d really like to be able to have something like brush:user and brush:root so that content in <pre> tags could look like:

# command typed by root goes here

% command typed by a regular user goes here

and the # or % and space is automatically included.

I know the “Developing a Custom Brush” instructions are here:

http://alexgorbatchev.com/SyntaxHighlighter/manual/brushes/custom.html

but I still have no clue to get close to achieving what I’m looking for. Does any such brush already exist, or can anyone give me a shove in the right direction for building it?

Thanks!