Existing .htaccess

I have a question, I am about to install vbseo for the first time. I have an existing .htaccess file for my CMS (already has custom rewrites done). Will installing vbseo have an impact on my existing rewrites / .htaccess file? Do I need to merge the two .htaccess files?

Apologies if my question sounds noobish :P but I am new to this realm of SEO.

If you are installing your forum in the same location as your cms, then yes, you will need to merge the htaccess files. This may or may not work depending on what you are using for a cms.
If your fourm is in a separate folder, ie,, /forums, the htaccess for vbseo goes in /forums so your cms rules will not be effected.

Cheers thanks, they are in separate folders.