how to design PCR site-directed multiple mutagenesis - (Mar/24/2009 )

the cloned gene is about 1kb, there are 8 codons i want to change by PCR method. but these codons were scattered in the sequence. i read several articles on overlapping or megaprimers PCR, could some people give me some ideas or experiences how to carry out this? or it's difficult to realize?

Have you considered having it synthesized with the changes? $750 will do it, and it may be worth it, given your time.
Geneart, DNA2.0, Blue Heron would all love to do this for you, perhaps for less.