how to unpack a dll file which is UPX packed but also the headers are changed?

Question

I have a file which is UPX packed. Is there any way I can change the headers and still find it as UPX packed? And how do I unpack it ? I tried a lot of tutorials and I am fed up as all explain the same method which doesnt work for me. the same problem is mentioned in the following : http://www.reteam.org/board/showthread.php?t=2670 I am not a well versed reverse engg.. :( jst a noob .. any ideas will be really helpful.