You can configure a route-policy in a "Localized Policy" and then reference that (local) route-policy in the "Policy Name" dialog box. In my test example here (see attached screencap as well) I created a "BGP_LOCAL_PREF" route policy in my local policy:
route-policy BGP_LOCAL_PREF
sequence 10
action accept
set
local-preference 100
!
!
!
default-action accept
Then I reference that route-policy in the BGP template. In my case, this is an outbound policy in VPN 1. It is used (obviously) to set the local pref to 100 and send that to the local BGP neighbor.
Hope this helps.