Do it manually in vista like this. Dont thank me thank Richard Miller I just dug up the link and then checked Vista for the registry keys, and changed a few things. If it doesnt work then you can blame me for that.
Link
Registry key - HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\HidIr\Remotes\745a17a0-74d3-11d0-b6fe-00a0c90f57da
Registry value - CodeSetNum7
Registry value data type - REG_DWORD
This setting also requires deleting the following registry values:
Registry key - HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\HidIr\Remotes\745a17a0-74d3-11d0-b6fe-00a0c90f57da
Registry value - CodeSetNum0
Registry value - CodeSetNum1
Registry value - CodeSetNum2
Registry value - CodeSetNum3
Note: I verified the registry keys are there, I have not yet verified the registry keys work. I will try this as soon as I can, but for now you will just have to try it in vista and see. I used 7 here assuming you already used 1 or 8 on the 2K5 MCE machine. If 7 doesnt work try 1 2 or 3. (insert registry hacking can be bad disclaimer here)