http://www.psychodogstudios.com/betterbodies/downloads.php
>> get the tutorial called "Tutorial for making a pair of shoes" (the page is all messed up in opera for me, but works fine with firefox). It explains how to physique a pair of BB shoes, but the workflow is just the same with chest meshes, and still applies for non BB meshes.
Another tutorial you may find interesting (although I did not learn from it myself):
http://mantodea.tygirwulf.com/tutorials/physique.html
I think there's also an other tutorial written by Phyntoswap (sp?), but I dont know where to find it. Probably on his website.
As for your warhammer cuirass, it is strange, is it a simple mesh you created and exported? If so then the difference is that here you are trying to combine your work with a rigged mesh, which I'm guessing you didn't do with your warhammer armor (although i have no idea, i dont know what it looks like).
edit: if you dont have 3dsmax 3, 4 or 5, you wont be able to export physiqued meshes since only the official exporter exports the physique modifier, you'll want to use the skin modifier instead, which the niftools plugin can export.