WOW, what madness.
Thanks for the access. I think I kind of got it working. The Dreamhost build of PHP is whacked- apparently, it chokes on trying to find "index.php/blah" as per the RewriteRule- it never finds it and ochiba never "runs". I don't know if the "cgi.fix_pathinfo" param would fix this, but you don't have access to php.ini to try it out.
Anyway, two seemingly minor modifications makes it work:
This sends PHP the "path_info" as part of the GET string, instead of a real PATH_INFO. Thank god for the Apache folks.
< RewriteRule ^(.*)$ index.php/$1 [L,QSA]
> RewriteRule ^(.*)$ /index.php?$1/ [L,QSA]
This converts the path_info kludge from the .htaccess into what ochiba expects.
< $path_parts = explode("/",$_SERVER["PATH_INFO"]);
> $path_parts = explode("/","/" . $_SERVER["argv"]);
Another thing I noticed is that the caching doesn't work for some strange reason. You have to turn it off, or else you'll get stale cache reads.
Also, there are issues with the setuid behavior when it creates directories; I had to manually chmod 755 on thumbs and thumbs/00/. images/ and images/00/ don't need it in the default because of the way it works. This can be addressed by adding a umask call prior to the mkdir()s in post.php and process_image.php. Otherwise, you'll have errors when it gets to thumbs/01/.
Finally, /stats doesn't work because it appears Dreamhost has set that up as a special URL so ochiba never even gets that request. Madness, I tell you!
I left it set up at the site you provided- let me know if you notice any oddities I missed.