What I do is run "white plastic trunking" down... I have some
piccies, but they're big... if you want me to mail them to you, drop
me a note off-list.
I had the
same
problem and used round black plastic trunking purchased from one
of
Mr Harrison' organisations. 4 runs of CAT5 will happily fit into one trunk
cant remember if it was 18mm or 22mm but doesn't stand out too much. (Only
3
CT100 though)
If you are going around corners etc make
sure
you thread the wires through the dismantled peices and then when it is in
roughly the right place get happpy with the silicone!!
We silconed a piece of pipe through the
cavity wall before starting which made life easier and should be a bit more
waterproof as it goes into the back of the round terminal box thing we used
to
terminate the pipe.
HTH
Paul