I have the wiring diagrams in .pdf for Square D buck/boost xmfrs. The
X wires are the heavy wires and the H wires the thin wires. X1 and X2
are the ends of one winding. X2 and X3 the ends of another winding.
The other windings are similar. Anyway, if you send me an email I'll
send you the .pdf of the wiring manual. Then you will be able to
figure out how to wire the thing. It should be easy enough, just
measure the output in one random configuration and you will be able to
tell what's what by looking at the manual.
Eric

Have a wiring diag:

http://oi59.tinypic.com/v3fuog.jpg

How to wire it isn't the question. Which wires are H1, H2, X1, X2, etc. is
the question.

Series light bulb or Variac (will use 120 mains for testing as that is the
only Variac I have...) seems the answer.

Remaining question: are H1/2 and H3/4 primary windings interchangeable? X1/2
and X3/4 windings interchangeable?

Thanks.