Hi David,
Are you using an email program or a champion challenger A/B test ? If it's anemail program, just run it on your smart list. If a champion challenger, create a batch smart campaign with the smart list as a target and use an send email flow step, using the test group as the email.
In any case, just send the email as usual, and let Marketo randomly assign each lead to a variant.
Now I would be a little suspicious about the relevance of a test with 9 variants. If you end up sending each variant to less than a few thousands of people, the statistical relevance of the result will be questionable.
Also, avoid testing multiple criteria on the same time, you'll have a harder time making sens of the results.
-Greg