Connect your guitar to the wah and plug that into the mesa's normal input. There should be an effects send jack and an effects return jack on the rear panel of your amp. Connect effects send to input of your zoom and then connect output of the zoom to the effects return.
Also, if you do this, don't use any distortion or overdrive on the zoom, they don't really work in the fx loop. I don't think you would want to anyway, since youre using a real mesa, wish I could afford it lol. The effects should sound a lot nicer once they're in the loop.
Btw I knew active eqs affected each other but didnt know how they did, that's all! Any progress on them yet?
Hope I've been of help :)