I have a D-Link DSL-500 modem/router, which uses a Helium chip (or
chipset?). Apparently the CPU comprises of 2 ARM7 processors.

The flash memory appears to be 2MB (16Mbit) large, including boot space.

I've been toying with the idea of making some form of emulator so that I can
load the firmware and play around with it, and, eventually write my own.

What I'd love to be able to do is load m0n0wall onto it, but it's a bit too
big. There appears to be a version of GCC capable of compiling
ARM-compatible binaries, so I don't know if what I'm talking about is
feasible or just plain stupid.

Anyone else ever done anything similar?

I've heard of people flashing routers to run cut-down versions of Linux etc.
but there seems to be a lack of information regarding this router...