Create a WSP file manually

http://www.theartofsharepoint.com/2007/05/how-to-build-solution-pack-wsp.html

http://www.chrishines.com/techblog/default.aspx

http://msdn.microsoft.com/en-us/library/aa543741.aspx

http://geekswithblogs.net/evgenyblog/archive/2008/01/27/118966.aspx