I am not a Java Developer and i didn't had any experience in either of EJB 2.1 or 3.0 but I studied only on weekends for 4 months and i was able to clear the exam with 92%.
The material i found most useful for beginners like me is EJB 3 in Action by Debu Panda, Reza Rahman and Derek Lane I used Netbeans 6.5 for practice with Glassfish server. The most important materials especially if you are appearing for SCBCD are Specs and Enthuware simulator.
I started on the 21st of may and gave my exam yesterday (18th june), which is less than a month. I passed with a 75%. I spent no more than 1-2 hours a weekday and 3 hrs weekends.
Although I am not so proud of the score and I could have done better if I had some more time, I think if you are short of time, reading oreilly and using the Enthuware simulator are the best bets. That's what I did. I read only the EJB roles part from the specs, nothing else. If you have even a couple of weeks more than what I got, I am sure you can score in the 90s.