You can configure and point users to an intermediary VS with an associated pool containing two members: your two mentioned VS. In these two VS, configure your connection limit or connection rate limit as per your requirement. If you want an active/backup scenario for your two VS you need to configure also priority group in the pool.
teemo_13 definitely what Amine_Kadimi said. Another option is if you have a BIG-IP DNS license you can use health monitors on it to respond with specific destinations based on information it receives from that health monitor but it definitely wont be as responsive to connection limits as the virtual server option would be.