You should be aware that cloaking techniques are frowned apon by the search engines and using them may very well get your sites banned and removed from their indexes, ultimately having exactly the opposite effect that you expect.
The public_html directory is not used at DreamHost, instead each domain (or sub-domain) you host will have a corresponding directory in your home directory, this will have the same name as your domain. For example, if your domain is mydomain.com, the corresponding directory will also be named mydomain.com. this is where your site files should be placed.
Here at DreamHost, you do not need to place your cgi files in a cgi-bin directory, but you can create this directory yourself (in your domain directory) and place your cgi files within it if you wish.
Edit: Beaten by matttail, I must remember not to get distracted while typing forum replies
Save [color=#CC0000]$50[/color] on DreamHost hosting using promo code [color=#CC0000]SAVEMONEY[/color] ( Click for promo code details )