Yes, I've seen books on how to do it. My ex-gf has a book on how to create really cool clothes from old T-shirts (men or womens).
It's called Generation-T
http://www.generation-t.com/ and the book is found on Amazon (or your local library or bookstore )
http://www.amazon.ca/Generation-T-Ways-Transform-T-Shirt/dp/0761137858.
As for myself, I didn't get around to changing my shirts and there's a couple I've been wanting to do, but I haven't yet. I'm not so crafty when it comes to sewing.
I wear boy-tees from time to time, or sleep with them 'cause they are big, long, and comfy. I get away with wearing the boy clothes at this point, because people just look at me and see "Dyke" and I don't really care, because I am lesbian and I get hit on a lot by other lesbians. So, hey, a cool boy-tee can have it's benefits.

I know a lot of women (not just all in the lesbian community) that wear boy clothes sometimes.
Although, if you are just starting out with transition, you may want to avoid wearing boy-ish clothes as it can confuse people. And I know a lot of butchier lesbians get called sir sometimes (or a lot, depending on how much the boi it up), and that's not something you may want when starting out. One of my exes, for example, would be called my boy-friend, and once she was called my son (that creeped both of us out). Even though she had huge breasts, she still got picked on from time to time. I usually don't get sired because I still add a dash of femme to that style, and know how to wear a style well. So, wearing boy clothes in a girly way can be done, but you've got to know what you're doing and how to pull it off.
But yeah, check out that book because you could invent some really cool tops.
--natalie