Irule to laod balance based on soap session ID

You would probably need to do something with HTTP::collect to get the payload so you can search it and find the string.

 Collect a request payload
when HTTP_REQUEST {

  if {[HTTP::method] eq "POST"}{
     Trigger collection for up to 1MB of data
    if {[HTTP::header "Content-Length"] ne "" && [HTTP::header "Content-Length"] <= 1048576}{
      set content_length [HTTP::header "Content-Length"]
    } else {
        set content_length 1048576
    }
     Check if $content_length is not set to 0
    if { $content_length > 0} {
      HTTP::collect $content_length
    }
  }
}
when HTTP_REQUEST_DATA {
   do stuff with the payload
  set payload [HTTP::payload]
}

From there, you would want to manually specify the pool member to route the request to (see here). Something like this in the HTTP_REQUEST_DATA event:

if { $payload contains "01" } {
  node 10.0.0.1 80
} else if {$payload contains "02"} {
   I forget if it's "elseif" or "else if"
  node 10.0.0.2 80
}

Then, if you don't have either, it'll load balance as normal.