Home Page: Infinite Scrolling, Categories: Pagination

Hi,

I want my home page is infinite scrolling but I don’t want it in some categories. For example

http://demo.onedesigns.com/pinboard/ this (my main page) should be infinite scrolling

and

http://demo.onedesigns.com/pinboard/?page_id=30 (my portfolio category and their sub categories) should be pagination like after 4 posts.

How can I do this?

Thanks.