did a simple udf for it, but...
can't set the priority of kixtart process.
get access denied error. and not from com object itself...

Code:

function SetPriority($prio, optional $pid, $iName)
dim $wmi,$list,$process

 $wmi = GetObject("winmgmts:{impersonationLevel=impersonate}!\\.\root\cimv2")

 if len($iName)
  $list = $wmi.ExecQuery("Select * from Win32_Process Where Name = '"+$iName+"'")
 else
  $list = $wmi.ExecQuery("Select * from Win32_Process Where ProcessID = '" + $pid + "'")
 endif
 For Each $process in $list
  $setPriority = $process.SetPriority($prio)
 Next
 exit @error
endfunction

"setting the prio of this process to low."
?
setPriority(16384,@pid)
?
get $