I actually took women's studies in university (just one first year course). I think a large problem is that men are afraid to really study these things for the very reason of "machoness." They pretend that there's no real useful applicable information there to be had, to themselves; and to their detriment. I could say that, to a lesser degree, this applies to sociology in general.
Being a guy, I think it's important to be tough, to stand your ground, to "be a man." When I say "be a man" what I'm really saying is: be a self respecting, self-confident individual who doesn't let fear compromise their true self; but because I'm a guy, and because I am who I am, I see that as "being a man" when applied to myself; the important thing is knowing who you are and being that person with full confidence.
"Macho" in the sense I think we're talking about is something almost opposite. It reeks of insecurity because when a man is *acting* macho, they are abandoning their true persona in favour of a false persona which they believe will be more accepted. It's that belief which indicates the insecurity because it's based on their assumption that a demeanour other than their own self will be accepted, but their own true self might be rejected. It's obviously a ridiculous belief, but it requires courage to disprove, and self confidence, the very things that are lacking in the first place.
I think everyone including myself is like this to some degree, but I also think life's too short to spend too much of it being someone you're not; I'd imagine it's really exhausting too.
Back to the original point: how to encourage men not to be afraid to actually learn about feminism (and not run away in terror when confronted with concepts like separatist feminism).
This might help: I studied *psychology* in school, but in fact did not become a *psychologist* nor was ever labelled as such...
I formed my own informed opinions and I learned things which benefitted me (selfish man that I am).
I think the same applies to any other serious field of study.
[edit: typos etc.]