Since Dreamhost doesn’t have this feature as one click install like you get when installing Google Apps, you have to do it manually (bleah… manual work sucks).

Here is a tutorial in 10 easy steps and images (cool huh ?):

1. Go to Domains -> Manage Domains in your DreamHost account and select your domain:

2. Hit the Delete Button (This will delete the association between an user and a domain) 

and you will get something like the picture above

3. Click DNS

4. And you will need to edit here, leave the nameservers alone

5. now in the Name field add: www, select Type:  CNAME and Value: pub-xxxxxxxxx.afd.ghs.google.com where pub-xxxxxxxxx is your unique Adsense for Domains ID (you’ll find this on the Adsense Setup-Adsense for Domains). Example below

6. After adding that DNS now is strait forward, you just need to add 4 more DNS records

7.

8.  LEAVE BLANK means not to write a darn thing, Adsense guide says to enter an @ but is better not to do it
9. After you added all, go to google.com/adsense/afd-add-domains
10. Send me a beer if it helped at http://giveabeer.com