Privacy Statement and Terms of Use as well as settings and edit pages use portal admin skin.

if you need a dedicated skin for your Privacy Statement and Terms of Use pages, create ordinary DNN pages, add Text/HTML modules and paste the text. Replace the skinobject instances in the portal skin with internal links to these pages.

Specify Different Skin only for Terms and/or Privacy
One easy way is to change your Terms and Privacy links (as Sebastian said) from the skinobject-created links to manual links but, instead of creating dedicated content pages, just append the "skinsrc" querystring value to the link URL to specify whatever skin you wish the target page to use.

Example:
If I had a custom skin "MySkin" installed as a HOST skin (available to all portals), I'd add the following to the end of my TERMS link url:

   ?SkinSrc=%5bG%5dSkins%2MySkin
 
If you want to play around with this and have DNN show you the querystring extension for a certain skin installed on your site, go into any page's SETTINGS, pick a page skin and click the "Preview" option.  The querystring for that skin will show up in the preview page's URL.


Alter Layout of Terms and Privacy
The contents of Terms and Privacy are "HTML aware".  In other words, you can edit the content and add your own inline HTML/CSS (and JavaScript as shown here) if you need to restructure the layout of the content itself.
 
For DNN 4.x, Terms and Privacy content can be found/edited under:  

 ADMIN->LANGUAGES->LANGUAGE EDITOR->MESSAGE_PORTAL_TERMS.Text 
 ADMIN->LANGUAGES->LANGUAGE EDITOR->MESSAGE_PORTAL_PRIVACY.Text
 
Also note that editing the content of Terms and Privacy will only affect the portal you are performing the editing from.  Other portals' content will not be affected.


Cheers!
-mamlin