The process took 1 day. I interviewed at EY in Sep 2009
Interview
E&Y interview process just consists of online screening and two 1 on 1 half hour interviews. The interview is mostly behavioral questions. The core skill sets that E&Y and other big 4 accounting firms look for are teamwork, leadership, analytical and communication skills.
If you are well-prepared and have many extra-curricular activities, you should have no problems answering most of questions. It is important not to ramble and answer what you are asked. Don't memorize answers and just come up with a list of stories that can be used for behavioral interview questions. The question they ask is pretty typical and as long as you go through behavioral questions you can find from Google, you should be fine.
I did not prepare well for this interviews, so I did not do well, but I am sure you will do fine. Remember practice!