Reply to Traktor Pro + External FX unit - can it be done?

Hi all,
I can't seem to find any conclusive answer/solution to my problem.
I want to use my Alesis Air FX as an external FX unit in Traktor.
Currently I'm having to use the FX send/return on the back of my PMC580 mixer which if fine except that I can't hear the effect on my headphones or booth speakers since it seems to be applied only to the master output of the mixer.

Ideally I'd like to route it as FX #3/4 on Traktor.
From what I can gather so far the external fx send/return seems to only be able to be used for DJs who want to treat Traktor like an external FX unit - is this the case? Is there no way of having traktor route its audio through an external FX unit prior to it leaving each individual channel?

Thanks in advance
Ollie