I have tried everything (including the wooden wrench in Cyclic itself) and pretty much any wrench
won't work. The only thing I've ever found that does, is the redstone torch method, you will know it works because it will give a message in (in the area where held item names are shown, not in chat) saying "Blocked cable connection <direction>" or "Restored cable connection <direction>" plus it will "mark" that direction
yellow--kind of like putting a
yellow plug on there--anyone who remembers
BuildCraft's Pipe Plugs will know what I mean.
For example, right click with a redstone torch on a connection facing east, the east side of the pipe will be
yellow, and a message will be shown:
Blocked cable connection east.
Do it again and you will see it disappear and message:
Restored cable connection east.