By far the easiest is to change your plans and connect to the parking
lights instead, they are always on when the low beams are on (and when
the high beams are on). There is an options connector in the fuse box
just for that sort of use. See
http://www.geocities.com/ng_randolph/Civic/civic_info.html

However, you probably have your reasons for wanting the low beams. There
is a bundle of fat wires going from the light switch on the steering
column down to the fuse box. For easy access, first remove the lower
dash cover (the plastic part that the fuse box lid sits on). It is
mounted with three screws along the top edge and hooked on a set of pins
at the bottom. Then remove the knee bolster (metal part you see after
removing the lower dash cover). One bolt on each side, then lift up and
towards you. It is hooked on a pair of metal tabs. It is not strictly
necessary to remove the bolster, but it is so easy to do and gives so
much better access you'll be glad you did. Now look for a fat wire, red
with a white stripe. That is the low beam wire BEFORE the fuses. If you
tap in here, be sure to use a wire tap designed for that large gauge of
wire so you don't damage the wires (i.e. you need the yellow ones, the
blue ones will cut strands in the wire). Also, be sure to put an in-line
fuse within inches of where you tap into the wire. I like the fuse
holders listed here: http://tinyurl.com/3gwlw (leads to part number Part
Number 082-160 on http://www.partsexpress.com). Rather than using
regular wire taps (http://tinyurl.com/awhlg) I like
http://tinyurl.com/dwxc7, as you can easily disconnect when needed.