<p>How can I build a native Mac OS X installer for my application, on a non-Mac platform?</p>

<p>For example, I have a windows pc and a Java application. I want the windows pc to build an installer (possibly inside a .dmg archive) that works with Apple installer.</p>

So, a couple of quick questions.
First, why do you want an installer? Most Mac users prefer apps that are just drag installed. If you are not writing Mac OS X specific code it is hard to imagine you need to place bits in special places, like Application Support or LaunchDaemons. Assuming everything you have just goes in one folder why bother with an installer at all?
Second, why would it be a problem to build the Mac installer on a Mac? Surely you have a macintosh around to test the app (you are not just blindly shipping it for Mac without testing it on a Mac, right?).
Okay, having said that, assuming you still have a good reason to actually build this on a PC, there are some bits that are not going to be easy. Basically a .pkg is a bunch of text scripts, localizations, an archive file (Archive.pax.gz), and a bill of materials (Archive.bom).
Assuming not much changes between builds, you can make the installer on a Mac, and then just rebuild the bom and the pax.gz, replace them into the existing .pkg, and batch a few pieces of metadata. The pax should be easy enough to deal with (pax is a standard archive format), but the bom file may prove a bit trickier, since I do not believe it is publicly documented, and I doubt the tools for creating them (mkbom) are part of darwin (not opensource). So you are going to need to figure that out and write a custom tool to create the bom file.
In other words, this is likely to be a large amount of work.