iRule Events where STREAM::enable is Allowed

Does anyone have a definitive list of iRule events where STREAM::enable can be used? I've been trying to use it in a clientside context in the HTTP_REQUEST_SEND rule, but it doesn't seem to have any effect.

What I'm trying to do here is to take action based on the result of an ICAP server (integrated with a request adaptation profile), but ignore the actual content ICAP returned. I'd like to modify the original request instead with a Stream profile.

From what I can gather, ADAPT_REQUEST_RESULT fires after HTTP_REQUEST (the iRules order page doesn't have the ADAPT events), so I'm left with a limited number of events where I can modify the request. I've tried both HTTP_REQUEST_SEND and HTTP_REQUEST_RELEASE, but neither seems to actually execute the STREAM::enable command.

Here's an excerpt of my iRule:

when HTTP_REQUEST {
  STREAM::disable

   ... snip ... some standard, non-stream related commands
}

when ADAPT_REQUEST_RESULT {
  if { [ADAPT::result] equals "bypass" } {
    set need_stream 0
  } else {
    set need_stream 1
     reset result to bypass to ignore response from ICAP server
    ADAPT::result bypass
  }
}

when HTTP_REQUEST_SEND {
  if { $need_stream == 1 } {
    clientside {
      HTTP::uri "/rewritten/uri"
      STREAM::expression {@FIND@REPLACE@}
      STREAM::enable
    } 
  }
}

Thank you in advance for any suggestions.