claims augmentation support

We are currently using F5 in front of SharePoint to validate users using PKI certificates, provide SSL off-loading, and manage load balancing to SharePoint WFEs. I would like to use the F5 for claims augmentation as well. The F5 can query an attribute provider as part of the claims process, but I do not know how to query (access) these session variables in the F5 to augment the claim passed to SharePoint. I am the solution architect, not a true F5 expert. Any insights would be much appreciated. Thank you. (PS - nothing came up in my "claims augmentation" search)