I'm positive IOS30 will work (i think any non-fakesigned IOS will work actually, but since IOS30 has been stubbed I recommend installing an older non-stubbed non-fakesigned version of IOS30, who's sole purpose is to allow the hackmii installer to run)
I used to have cioscorp 3.4, but restored an older nand dump because i couldn't stand it any longer. But while I was 'corped, I also got the no vulnerable IOS error, and the only change I made to my wii was installing IOS30 v1040, then reran the hackmii installer, and it worked fine.
I suspect installing any non-fakesigned IOS will work, so if some1 chooses to do so with IOS34, I think that will work too. But I don't know what that IOS does (it may actually serve a purpose in allowing 'corped wii's to play backups via the disk channel, i have no idea), so that's why I prefer to use IOS30 (as it was an older system menu IOS that got stubbed long ago and is definitely not used anymore (unless your firmware is REALLY outdated))
EDIT: forgot to give credit where credit is due, it was Zektor (author of the 4.2 safe updater) who first suggested installing IOS30v1040 to resolve this issue