I've written linux-based command-line tools for programming and dumping flash memory on dsPIC chips. They're work like prog84 and dump84, the command-line tools for burning PIC16xx and PIC18xx series devices. I use them with my JDM-style serial programmer, which can be trivially modified to work with the dsPICs. They're pretty basic, but they work. They should be easily modifiable for other hardware.
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What would be really cool if is someone would extend the gpsim emulator to work with the dsPICs...
Homer Reid