downtown? Portland or Vancouver?
Me and the recumbent gang do this every year. Here's the web page about it:
with links to the map and the cue sheet.
Jason's directions sound like what was published by Andrew Black. Here's the map that goes with the directions:
FWIW: I prefer going up along Washougal River instead of around Cape Horn. It's a bit less traffic and an easier climb. It's nice either way.