Yes, SCEA 2 is discontinued. I was in the same situation as you. I was preparing for SCEA 2 part 1 when it was cancelled, but in my case I already had the voucher. So, I could take part 1 and, as I also had the voucher for part 2, I am already working on the assignment.
If you don't have the vouchers, I think it will not be possible for you to take SCEA 2.
The most important thing is that you should already have a voucher for Part II exam. Since for Part I & III, the exam is also 310 prefix. You just need to buy voucher for prefix 310 exam for them. However, if you have not bought the voucher for assignment, I think you cannot buy one now.
Moreover, although you have got all necessary voucher, you must complete the exam before end of Dec 2008.