As of now I'm not preparing for this exam (will start after couple of months), but what I've heard so far:
1) Cade & Sheil book is still good for the exam.
2) For other books, you can refer SceaBooks. Since lot of those books focus on architectural concepts, those are still applicable for JEE 6.
3) For parts which are not covered in Cade & Sheil (which are new for JEE 6) - you can refer Java EE 6 tutorial
I am also preparing to take the 1st part of OCMJEA 6 (the exam).
I compiled a huge list of link to notes, mocks, thoughts - mainly from this forum and google ... I passed them. I read the JEE tutorial. I read the Guide.
I also bought ePractizeLabs preparation kit ... it has theory on it ... It has some good questions, but still I can't comment if it is ok for the exam. it is the only available preparation kit for OCMJEA 6, yet. WhizLabs said they will need atleast one month to publish their version, but I just have no time to wait ... It is annoying they keep high price for their OCMJEA 5 , I would have bought that, too.
So, anyone that wishes to contact me - write a PM We will need to help eachother on the parts 2 & 3, too