I studied HF EJB regularly on my way to work in the train. I did not rush the preparation but I tried to use whatever little time was available on hand. I am a busy professional working long hours on a project that is going to production shortly. Reading the various postings in this forum regularly will be quite helpful in your preparation.
I would suggest going through HFEJB completely, cover to cover. However, don't try to memorize everything you read. Get a "feeling" for the material. Then go through it again, but only focus on the areas you definitely do not understand; this makes the read much faster and allows you to reinforce the material you have previously read.
Once you have gone through the book a few times, I would suggest downloading an exam simulator. I found the EJBPlus simulator to be quite helpful. While there are errors in it, as well as spelling and grammar mistakes, it really gets you thinking about EJB. I found that it helped clarify the areas that I had trouble with originally from HFEJB. It also made me appreciate the spec. I found that the spec was useful when I didn't want a saccharine-coated explanation of something from HFEJB; I went to it when I wanted the low-down.
Take my comments FWTW. I have not yet written the SCBCD exam, but I am prepared to write it this week.