DirectAccess f5 LB DIP's

All-

I am trying to configure a DirectAccess hardware loadbalancer and I used the local IPs of the server, which is apparently wrong.  I have DirectAccess setup on Server 2012 with a multihomed design front loaded with a pair of f5 LTM's.  My question is what IP's should I use for the external and internal DIP, that will be converted to VIPs.  

Do I use the f5 pool VIP? Do I need to setup the server with dual internal and external IPs?  This is highly undocumented.

Thanks!

BR