You can push it around with a classic or guitar controller. It just needs to be patched to think one of those is connected and read the SI registers instead of the wiimote extension data.
1) No reason to do it.
2) You would have to do a lot of modifications.
3) Messing with the SM is dangerous.
4) Again, no reason to do it.
LOL, this from the guy who always recommends to install priiloader aka the most invasive and dangerous system menu modification of all.
Priiloader certainly has the potential to screw up the SM, I don't deny that. I made it clear in the thread about priiloader causing bricks. However, it's install process has proven quite safe (with the exception of v0.5, which was more a result of TT fail) and it is very beneficial in the long run.
In this case, the user wants people to attempt something of little to no value because he is too lazy to use a Wii remote. I don't know if the change is even possible (you might though), and I don't think it's worth the risk.
Bzzzzt, wrong. Did you even read my reasons? Besides, it's worth it for even more than what I mentioned.
Ever had one of your little nieces or nephews break one of your Wiimotes? I have. That is painful, especially when I only use the Wiimote minimally. In fact, the only thing I use it for is to SELECT MY FREAKIN' DISC CHANNEL. After that, it gets tossed somewhere else. Why not have the ability to cut it out of the equation, period? Not to mention batteries that you have to keep paying for. It would save money.
And, as if I even had to mention it, the very same problem would be solved for everyone.