Catchall for subdomain

[damon]

I'm trying to setup a server alias for a subdomain. This is for a community site with member generated blogs. So the idea is to have a blog url like http://max.blog.example.com for user max. So the alias is *.blog.example.com

The instructions in the php blogging module for url's are

a) 	requirements
    1.	webserver with mod_rewrite module enabled
    2.	usage of .htaccess-files is possible
    3.	make a dns catchall entry to a subdomain at
	*.blogs.yourdomain.com in your nameserver zonefile
	In this example the postnuke user "max" will
	be able to reach his blog typing the url
	max.blog.yourdomain.com

b)	and what's to do then?

	Store the folliwing ruleset in your .htaccess-file

	RewriteCond   %{HTTP_HOST}                 ^www\.[^.]+\.subdomain\.domain\.tld$
	RewriteRule   ^(.+)                        %{HTTP_HOST}$1          [C]
	RewriteRule   ^www\.([^.]+)\.subdomain\.domain\.tld(.*) [url]http://www.domain.tld/index.php?module=pnWebLog&func=UnameRedirect&uname=[/url]$1 [L]
	RewriteCond   %{HTTP_HOST}                 [^.]+\.subdomain\.domain\.tld$
	RewriteRule   ^(.+)                        %{HTTP_HOST}$1          [C]
	RewriteRule   ([^.]+)\.subdomain\.domain\.tld(.*) [url]http://www.domain.tld/index.php?module=pnWebLog&func=UnameRedirect&uname=[/url]$1 [L]

I've created a subdomain blog.example.com and then created a vhost.conf in the conf folder of that subdomain, and created an .htaccess file with the above contents. (ran webmanger and restarted httpd) it's not working, I'm unsure if i'm following these instructions correctly in the "Plesk World".

What steps would you take to follow these instructions?

Thanks,