I've posted a similar question in alt.autos.subaru, but I'm looking
for other experiences or tips.

The car is a 2004 Subaru Impreza WRX with four almost new all-
season tires (Bridegstone Potenza RE960AS).  I've tried driving it
in the Sierras with Pirelli P Zero Nero M+S, which I didn't think
was that great in snow.

At least in California, the AWD with M+S tires is enough to get
me waved through R2 chain checkpoints.  However - I realize
there might be conditions where I still need to get out and put
on the chains if there's substantial ice.  I've tried installing the
chains I've got (Cobra cable chains from Quality Chain) in my
garage.  They attach via a series of bushings that are fitted into
a keyhole end hook.  The instructions state that it should be
done with the car parked, although it may be jacked up with
adequate safety measures (blocking the rear wheels).

So each cable attachment point has 8 bushings.  I could get
them to the 6th bushing on the inside and outside with these
new tires.  At that point there was still quite a bit of slack and
the cables seemed a bit sloppy.  I tried getting the outside
cable to the 7th bushing but couldn't.  The instructions said
to drive the car one length ahead (I didn't try) and retighten.  I
suppose they may be easier to retighten at that point.  There
are also some rubber adjusters available to take up the slack.
I'm not sure where to find them, but they seem like a good
way to make sure the chains are secure w/o overtightening
the side cable.  They also have a crappy keyhole clip that's
supposed to retain the excess side cable.  They don't seem
too secure, so I might just use velcro ties.

<http://www.qualitychaincorp.com/pdfs/passenger_install.PDF>
<http://www.qualitychaincorp.com/detail.phtml?sku=1034>
<http://www.qualitychaincorp.com/accessories.php?s=3&a=misc_parts&sku=0212>

I've looked up other instructions and seen different instructions
for ladder-type chains/cable chains, including:

* Turning the wheels in one direction to make it easier to
reach the connector on the inside of the tire.

* Attaching the chains on loosely, then drive one foot so that
the attachment points are vertically at about axle level.  Then
tighten.

* Using a jack.

* Lay out the chain in front of the car and drive over it so the
attachment points are near the top or axle.

** ** **

I know I can pay a licensed installer, but I can imagine being
in a situation where I need chains and there aren't any
installers.  I'm also curious as to whether it might be a good
idea to get another set.  The owner's manual says that chains
go on the front, but I've heard many indications that an AWD
vehicle with chains only on the front might be more likely to
spin out if the rear tires lose traction.