title of the question you posted is slightly misleading. there is no requirement of scjp to take scjea. scjea has got three parts . you have see this forum for more discussions.
SCJP and SCEA are different exams. SCEA has Part I, II and III. You have pass Part I before taking Parts II & III. SCJP has nothing to do with SCEA. Check this site... http://suned.sun.com/US/certification/java/java_archj2ee.html Go thru the posting u will find lotsa information for the exam...