I can back my wii from 4.2.e to 3.4 e with my nand file that is in the 3.4 E
You are Wierd. You didn't ask a question but rather made a statement.
Anyway. Yes you can provided you have bootmii/boot2 installed (dual flashes from DVD slot). If you don't then you can't.
Not really doing much Wii stuff these days.