Actually, I've recently been contemplating this exact thing. I'm new to DragonMech, but have been DMing Eberron since it was first published. Actually, I've been playing D&D since two years after it was first published, but I digest....
Eberron seems tailor made to host a mech insurgence, or at least ripe for porting ideas over to Highpoint. The first and most obvious thing is all the repair X damage
spells. Artificer/Coglayer or Artificer/Constructor seem like natural multi-class options.
The thing I'm wrestling with is the different concepts of "technology". In Eberron their advancements are basically along the lines of forcing elementals into Kyber Shards as a power source for transportation. An airship is propelled by a bound air or fire elemental, while land-bound vehicles use earth elementals. Would an Eberron mech use a fire elemental for heat and a water elemental for steam? That would pretty much negate the steam engine wouldn't it?
I am sure those inventive little Zilargo gnomes would be just as happy making clockwork mechs and adding an earth elemental to wind it up and give it an earthglide ability.
But Eberron has already taken the concept one step further... warforged. A warforged titan is nothing more than an animated mech. The warforged themselves are animated and awakened constructs for all practicle purposes. According to the source material they are basically masterwork armor filled with an elemental spirit, similar to the spirit from the elemental plane of water that animates a nimblewright.
Aside from that, my plan is to drop a Coglayer 5/Constructor 5/Steam Mage 5 into eberron via a transitive plane and see what direction my players want to take it. At worst they will want to seize his enchanted steamgun, at best they will help him find the way back and give him some good ideas on how to help the people of Highpoint (and maybe a few juicy fruits and vegetables to make him rich).
The party is currently in the presence of an NPC golem-building mage, so at the very least I can have the two of them hang out and brainstorm in the background of the setting. That way my players won't be too surprised when a mech exits the elemental assembly plant in Zilargo with a fire elemental in the boiler instead of needing fuel.
Once in Eberron, the gnomes will most likely become the premier mech builders, with other races only taking notice when power starts to shift in favor of the entity(ies) with the mechs. Count on house Cannith getting their fingers into this quickly. Lyrandar and Orien will be racing to get their hands on them. Especially Orien to guard the caravans and provide overland secured deliveries.
Steam cannons shooting down Lyrandar airships could swing the balance in Orien's favor quite firmly... until the first steam-powered gunships take flight, that is.
I haven't read anything about a walking city for the warforged. Is this a novel or a sourcebook that has this in it?
Anyhow... I don't see a tremendous difficulty blending the two settings. Of course in Eberron the thirteenth moon has been missing for a long while. Wonder where it might have gotten off to?