How to set my RDP ColorDepth to 8 bits in windows 7

I hope someone can help me out with this problem. I'm running windows 7 ultimate and I'm trying to make my remote desktop connection work on 8bits (256 colours). So far I found that I can create a .rdp file, edit it with a notepad and change this line session bpp:i:15 to session bpp:i:8
However, because of our network firewalls I'm only allowed to use RDP through a proxy, so I cannot use that solution.
Can anyone tell me how can I work this out please? Changing registry files, anythig. Thanks in advance.
Asked Dec 27, 2013

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