Maybe with changing the blog software? I use b2evolution. It´s in php.
With b2evolution you are able to blacklist domains but also only sub-domains. You always can choose to blacklist local (only at your blog), by reporting to b2evolution and you can you use their blacklist. But by using their blacklist you has to clean the blacklist each time as there are also general words like casinos, vegas etc. blacklisted.
And the blog is fully integrated into your domain (no blog subdomain):
www(dot)yourdomain(dot)com/blog