The Universal Inspection Engine (UIE) can be used to create persistence records for just about anything. A common use-case for UIE is to pull JSESSIONID strings out of HTTP headers or cookies and create persistence records from them. There's a write up here:
http://devcentral.f5.com/Default.aspx?tabid=63&articleType=ArticleView&articleId=48
This iRule, for example:
http://devcentral.f5.com/wiki/default.aspx/iRules/FixSelectPoolBasedOnSenderCompID.html
...uses UIE to create persistence for the FIX protocol. There is also some information in the Config guide (check the bottom of this page: https://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/LTM_config_guide_943/ltm_persist_profiles.html1193560).
In short, you're going to want to identify something in the traffic that can be used to identify and distinguish sessions, use UIE to pull this string out and then persist on it.