Carlton's example in Acts 13:5 was especially helpful for me, since the parallel
is easy to see.
I've also soaked up enough vocabulary in these messages to find the relevant
sections in Robertson's Grammar (p. 219 (i) Two accusatives with one verb) and
Richard Young's "Intermediate New Testament Greek" (p. 17 Double Accusative --
direct and predicate objects).
I now have a way of parsing this that makes sense to me, and which agrees with
most modern translations, and some people who know Greek a lot better than I do
who say that it is correct. This is extremely helpful.
Stephen Carlson's parsing also makes sense to me. Both ways of interpreting it
lead to the same meaning -- are they equally valid?
OUKETI - adv. modifies LEGW "no longer"
LEGW - vb. 1s pres act ind of LEGW "I say, speak, etc."
hUMAS - pron. acc 2p, subj of [EINAI] "you"
[EINAI] - vb. pres act inf of EIMI, obj of LEGW "[to be]"
DOULOUS - n. acc p of DOULOS, cmplmt of [EINAI] "slaves"