How do I create Sequential or Linked iRules?

Are there only the 2 rules assigned to the VIPs doing Pool assignment?

As if that's the case, couldn't you just use 'Event disable' in your test iRule if it's a test connection...

 
when HTTP_REQUEST {
 if { [HTTP::host] eq "testsite" } {
     Assign target pool (if this is the default pool, this can be omitted).
    pool testsite
     Do not process prodsite iRule
    event disable
  }
}

Cheers

Gav