You're on the right track - the settings probably
can not be applied. The DEQ has a lot more EQ settings than the DCX, anyway. The DCX is mostly a crossover with some EQ thrown in. They are too different.
But hey, why not use the DEQ in front of the DCX and link them together via AES digital? OK, there's the cost issue - but you don't have to buy them both at the same time.

That way you could have a very good, all digital system EQ that feeds into your digital x-over -- with some EQ on each x-over section.
You can EQ and tweak to your heart's desire.