The question your asking you posted in the code modifications forums not a support forum that I see and your not specifically asking a support question that i am seeing. The second linked thread explains our company policy on code modifications which should be clear there.
There is no way to alternate highlighting colors as thats not how the feature is designed. It is essentially designed as a payment add so not every ad will be highlighted only those that pay for highlighting. You must be allowing highlighting to all without payment. I explained how the feature works in my initial post above. If you wish to discuss changing how the code works you may discuss this outside the support forums in the mod corner. However our company can not guarantee you get any response from users.
If there are any support questions we can answer please feel free to contact us.