No command line is really necessary
Hex editing, maybe, but not hex coding
for a basic translation, you really don't need to go as far as ASM unless you really need to edit something that's hardcoded into the game, preventing it from being easily edited.
Well, you can't expect text files all the time, but they sure do come out. (Jet impulse)
Programming knowledge helps you get repetitive tasks done easily unless you want to edit and recalculate everything by hand.
Crystaltile2 works as a hexeditor and a graphics editor while it supports native DS files