Mexxell

I think it would work. I believe that BioChroma is mainly based in the Spiritual and Cognitive Realms, while at least Steelpushing and Ironpulling are almost entirely Physical. I'd say that an Awakened metal would be able to be Pushed and Pulled, though the Awakened object would probably fight back. Then again, as Kirkistan mentioned, we're not even sure that Breaths can be stored in metal, and it takes a silly amount of BioChroma to use metal in any capacity, so the odds that the question would be put to the test is slight at best.

I was just recently rereading Elantris when I got to the bit where Galladon explains what the Dor is to Raoden. From the way he describes it, it sounds an awful lot like the Dor is at least partially based in the Cognitive Realm, and is quite chaotic/powerful at the same time. We also know that Shadesmar is based in the Cognitive Realm. My guess would be that the power and chaos of the Dor affect world-hoppers' ability to access it from Shadesmar. The Splintering of Devotion and Dominion probably also have a hand it it, though my two cents is on the Dor's power.