Should I undo the EGR valve when changing glow plugs?

[jbach36]

I have to replace my glow plugs, and I guess I have to take off the crossover tube, which is full of sludge. I think when I take that off, I can get to the egr valve, is that right?

Anybody know how to do this on my model car? I heard I have to trick the computer into thinking it's still hooked up.

Thanks,

jeff 1991 300d, W124