Drupal in Gallery2 subdirectory

Hello!

I have a gallery2 script with clean urls in my rootdir http://mywebsite.com
And a drupal script used as my blog at http://mywesite.com/blog located at rootdir/blog/

I' ve successfully created some static drupal pages in my root dir.
For example http://mywesite.com/blog/about -> http://mywesite.com/about
For example http://mywesite.com/blog/contact -> http://mywesite.com/contact

using .htaccess

RewriteCond %{THE_REQUEST} /about
RewriteCond %{REQUEST_URI} !/index\.php$
RewriteRule . /blog/about [QSA,L]

RewriteCond %{THE_REQUEST} /contact
RewriteCond %{REQUEST_URI} !/index\.php$
RewriteRule . /blog/contact [QSA,L]

But I'm stuck at subdirs like forum/24354 or /user/55

I've tried
RewriteCond %{THE_REQUEST} /forum/(\?.|\ .)
RewriteCond %{REQUEST_URI} !/index\.php$
RewriteRule . /blog/forum/(\?.|\ .) [QSA,L]

But gallery's rewrite rules ignore it and give 404 errors.

Has anyone done this before?
Thanx