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Since your client dont have any time to chat online or through conf. its better to allow him to make changes on paper if those are just small changes in navigation stuff..or design and send them through email.
Personally, I prefer that the client manually marks up the pages and faxes the changes back to me. Of course, I'm assuming here that he's not rewritting whole blocks of text, just making minor edits.
Take a look at www.flyspeck.net
I've used this on a few sites, and it works great. I'm not related to the company that puts this out, just a satisfied customer.
I always though it redundant for a client to mark up a Word doc or send a fax, and then for me to in effect duplicate the changes in HTML. Having a CMS saves me time and clients $$$. Plus, I get to work on more exciting stuff :)
Before they send me their content, I make it very clear in my contract that all content must be final. If they have any edits, it will be an additional amount. Too many clients won't revise the content and will want to make 20 million edits to it once it's live.