1 - So then the keys will be in different formats? Why would that work?
2 - I've tried that function before when using different tutorial, but it didn't work.
3 - I think I'm doing everything right, but to no avail.
1 - Why wouldnt it? The keys are only stored in different formats, putty needs the putty format, openssh needs the openssh format.
3 - If you would be doing everything right it would be working by now. Post a ls -l output of your .ssh directory.