I had the same worries. The guy from B&B gave me a bunch of advice on how to do it. Basically you push the coil that encases the plug head out the plug boot and then remove that coil. Then I could pull the plug boot and slide the shielding over the high tension lead. When I had it done I put heat shrink over the now shielded plug line and then reassembled it.... Reversed what was done above and then shrunk the heat shrink.

It turned out to be a lot easier than I expected.

Chris