The four inch dryer vent is indeed the neatest way
to provide a great entry for coax and ground wire.
For great information on proper grounding, See the
tech. notes at the Polyphaser website:http://www.polyphaser.com/ppc_pen_home.asp
Don't be overwhelmed by how much they want you to
do to properly ground a station. It can be done for
lots less money than it might at first appear.
No need to use "new" wire outdoors for example.
Old scrap copper wire works great. Copper strap
can usually be had for a good price from upscale
roofers (Roof valley flashing) Instead of "cadweld"
Old fashoned hard silver solder can be used.
(Mapp gas in a small hand held torch will provide
enough heat) And it does not all have to be done
at once. I am still adding ground radial wires
to my station, Been at it for over 30 years now!