Oxy sensor for 93 V6

["C. Krafft" <ckrafft@olg.com>]

In reading the recent discussion and having the engine warning light going
on when my car is warm and sits at idle for more than about 30 seconds, I
started doing some research on the O2 sensors.  For the 93 V6 (I have a
100CS QW, there are two Bosch part numbers with a VIN number delineation.
Price is ~136 for early VINs and ~170 for later VINs.   The fellow at
Olympic Import Auto Parts in College Park MD warned against using the
"generic" part number, indicating that in addition to the obvious problem
of finding the right thread size, the depth of the sensor in the exhaust
pipe is important.
Sometimes these guys know what they are talking about, although I'm always
suspect. 
Anyway, my mundane question is how do you remove the old one.  Mine seems
to require about a 20 mm diameter socket, and fitting a box wrench in there
(if I even had a 20 mm one) is a bit difficult.  Of course you could snip
the wires and use a deep socket to get it off.  I was trying to avoid that
approach, if possible.  Any hints, or special tools for this?
Thanks,
Charles Krafft