set/overide session values via iRule

Try this in a VPE variable assign before your iRule event and then remove the iRule event and use an empty VPE action...

session.custom.logontype =

set logonname [string trim [mcget {session.logon.last.username}]]; 
if { [string length $logonname] == 0 } {
  return "99"
} else {
  if { $logonname starts_with "company-" } { 
    return "1";  
  } elseif { $logonname ends_with ".com"} then {
    return "2";
  } elseif { $logonname contains "company.net"} {
      if { $logonname contains "\\"} {
        return "1";
      } else {
        return "3";
      }
  } else { 
    return "1";
  }
}

Then in the action after the variable assign you can create a empty VPE action that checks the session.custom.logontype session variable value and proceeds down the branch needed.

Please let me know if this helps.

Seth