Does this look right?

htaccess

RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([a-zA-Z0-9\-]+)/?([a-zA-Z0-9\-]+)?/?([0-9]{1,2}\.[0-9]{2,3})?/?$ index.php?l=$1&s=$2&c=$3&q=%{QUERY_STRING}

nginx

location / {
if (!-e $request_filename){
rewrite "^/([a-zA-Z0-9\-]+)/?([a-zA-Z0-9\-]+)?/?([0-9]{1,2}\.[0-9]{2,3})?/?$" /index.php?l=$1&s=$2&c=$3&q=$query_string;
}
}

You should avoid "if" with Nginx. See http://wiki.nginx.org/IfIsEvil

I think this will work, but it's been awhile since I've used Nginx:

location / {
    try_files $uri $uri/ @router;
}

location @router {    
     rewrite "^/([a-zA-Z0-9\-]+)/?([a-zA-Z0-9\-]+)?/?([0-9]{1,2}\.[0-9]{2,3})?/?$" /index.php?l=$1&s=$2&c=$3&q=$query_string;
}