Andrew,
Hi. If you are running the Single-Tier option on AWS, you can use ssh to login to your instance, then type
mysql -u root -proot
to open mysql. The username and password are both "root". This is not insecure because the database is not externally accessible. I hope this helps.
BTW this is documented at the very end of the Single-Tier document. So it is a bit hard to find.
Jim Mooney