Creating JWS session tables

Yep, that's clear. Totally doable with an iRule, and you can store the data in the session table via the table command with the external token being the key and the internal token being the value. Pseudo code would be something like:

when HTTP_RESPONSE {
  set key 
  table set $key $internal_token $expiration_in_seconds
}
when HTTP_REQUEST {
  set int_key [table lookup $ext_key]
  if { $int_key ne "" } {
    HTTP::header replace header int_key
  }
  else { HTTP::header remove header }
}