There are good software packages to help you with the creation of successful doorway pages. WebPosition Gold can help you analyze each search engine and advise you how much to change each of these items. Another good tool is the Doorway Transposer . We recommend both of these programs and have arranged discounts for our members. A piece of redirecting java-script in the head tag doesn't prevent spiders from indexing the rest of the page as some believe, and it doesn't cause spiders to ban the page.
Many people use the method.
Nobody minds redirection in itself. What people and engines DO mind is redirecting surfers to places that they didn't want to go. Spiders are not sophisticated enough to sort out the hijackers from the rest so some engines have declared redirecting to be 'wrong'. It's the engines' failing - not the redirection. There are risks.