Hi Chris,
If you want to find a book for SCBCD, I strongly recommend you the book written by Kathy and Bert: Head First
EJB. This book is very good for preparing SCBCD, and I think it is the only reference that you needed.
However, since SUN's exams are vendor independent, it may not be suitable for the WebLogic exams, in fact, I dont know the objectives of WL exams, so I cant comment much here.
For the IBM 484 case, I used the reference SCWCD Exam Study Kit for Servlets/JSPs/Pattern part, and HF EJB for EJB part. I dont know whether this can happen in WL exams.
BTW, Oreilly has recently published the book: Mastering WL 8, maybe this can be one of the reference books that on your list.
Nick
SCJP 1.2, OCP 9i DBA, SCWCD 1.3, SCJP 1.4 (SAI), SCJD 1.4, SCWCD 1.4 (Beta), ICED (IBM 287, IBM 484, IBM 486), SCMAD 1.0 (Beta), SCBCD 1.3, ICSD (IBM 288), ICDBA (IBM 700, IBM 701), SCDJWS, ICSD (IBM 348), OCP 10g DBA (Beta), SCJP 5.0 (Beta), SCJA 1.0 (Beta), MCP(70-270), SCBCD 5.0 (Beta), SCJP 6.0, SCEA for JEE5 (in progress)