encoder indexing pulse

Since encoders seem to be a hot topic lately, I have a question of my
own. The NEMA42 Compumotor steppers that I have mounted on my Bridgeport
conversion are equipped with BEI encoders. I called yesterday to BEI and
they were nice enough to send me the spec sheets pertaining to my
encoders since I was clueless as to how to hook them up to my new
Camtronics DRO board. The plan is closed loop operation. OK finally to
the question. These encoders have dual channel (2A&2B channels) plus an
index channel. I want to use the index channel for limit and homing
switching in conjuntion with another set of optical switches. The theory
being the first optical switch is tripped when things are close and the
index channel would stop it right on the exact step every time. Using a
logic "AND" circuit. This is not my brilliant idea. The Vexta manual for
one of my 5 phase drivers suggested this method but not with an encoder
but a "timing" output( a counter gives a pulse for every 10 steps. The
manual recommends shutting the system down when homed this way. When the
system is powered up it won,t jump steps.
What kind of circuitry do I need to carry this out? The optical switch
would be one of those led units probably much the same as the encoder
itself. Probably a 5V input to power up the led. Could it be as simple
as putting 5V to the optical and hooking the output in series with the
index channel output and then to the parallel port? Would I need an
opto-coupler for protection of the PC? Any use for the second set of
encoder channels?