I haven't done this on our J, but I've done it on a number of non-tapered masts.
the trick to installing the pvc conduit is to drill two holes side by side about half the diameter of the conduit apart. Use the bent coat hanger through one of the holes pull the conduit up flush with the other hole so that you can drill a hole into the conduit and fasten it to the mast with aluminum pop rivets. You repeat this every three or four feet up the lenth of the conduit. Then you fill up the extra hole with another pop rivet.
