DS is simply not powerful enough - processors are far too slow and the system only has 4MB of RAM. The DS is roughly as powerful as the N64 but their architectures are different (N64 used MIPS processors, DS uses ARM). You need a system at least 5 times faster with an adequate amount of RAM to emulate a system of a different architecture at a reasonable speed.
Even N64 emulators for PSP are extremely limited. N64 emulators can only really be viable on consoles as fast or faster than the Gamecube.
Yes, ports are the only way to go on the Nintendo DS. Unfortunately, Super Mario 64 is actually the only N64 port, and i think it´ll remain as it. Wave Race would be cool on DS...
The DS cpu/s is slower and diferent architecture, doesn't have a FPU, and the maximum number triangles per frame is ridiculously low, so... it's 100% impossible, considering that after hells of optimization, one could get 0.5-1fps maximum.
Right so you want to play N64 games on your NDS?
It's not that it isn't possible to do this, it's just unrealistic.
The N64 actually is about the same power as the NDS, that creates a problem automatically in that running the original code is guarenteed to be slow since it is written for another processor. All perfomance enhancements on this are done by Dynamic recompilation of the original code. Although this does improve speed significantly it does so at the price of memory. The NDS just doesn't have enough for that type of thing.
Next comes the data in the N64 carts. This is loaded into memory as needed by the game itself. So basically you have to have a nice way of loading data from the NDS flash cart with the ROM image on it. This might be a bit tricky considering the current state of homebrew on it.
I'll cut to the chase, Overclocking won't solve the problem. The only way I can think of is do a binary translation of the N64 ROM. This omits the problem of the custom processor used in the N64 for audio and graphics aceleration. Thank goodness there was a handy way to get around that with the N64 (via HLE) for most games. (Conkers Bad Fur Day isn't one of those). Doing a binary translation is NOT emulation, this means you are in a very dark and forboding legal area. Likely on the illegal side with that.