Each MOTU interface has two FireWire jacks that are essentially tied to each other.  You can
go "in" or "out" of either one.

Our FireWire chain goes like this, starting at the computer's side jack:

    FireWire 800 output jack ->
    Short white 800-to-400 adapter ->
    Long, heavy gray cable (to stage) ->
    Larger (separate) repeater box ->
    Shorter black cable's "simple connector" end ->
    Black cable's lumpy repeater (sneaking under the screen to save length) -> 
    Shorter smaller gray cable (through the front of the rack) ->
    Lower MOTU interface ->
    Chained to another MOTU interface ->
    Chained to another MOTU interface.

We kinda hook this up in the opposite order, most of the time:

    Start with the light gray cable through the front of the stage
    rack, looped back into the lowest MOTU box so the cable won't
    pull out.

    Sneek under the screen to save a couple of feet of cable.

    Black cable tends to lie across the stage; the boxy repeater
    tends to sit near the leader.  Make sure it's not in a place
    to be stepped on!  Dead silence thereafter.  :)

    The long heavier gray cable back to the puter, through the
    short white 400-to-800 adapter cable.

A picture would be SO much easier to deal with.