FORTUNE — Dear Annie: For the past two and a half years, since I graduated from college and got my first real job, I’ve been lucky to have a terrific mentor, a couple of levels above me in the company. We get together for lunch, coffee, or just a quick chat at least twice a month, sometimes more. Not only do I really enjoy these sessions, but her advice and insights have helped me get some great assignments (and a promotion).

Now, she’s been chosen to spend a year running a new operation we are starting up in China. It will be very demanding and, on top of the 12-hour time difference between here and there, she is going to be extremely busy. I’d like to continue our relationship, but I’m wondering, how realistic is it to expect that? — Waving Good-Bye

Dear Waving: The short answer, from Nicki Rich: “If you both want it to work, there’s no reason why it can’t.” Rich, a cloud computing executive at IBM (IBM) in Beaverton, Ore., has worked with about 25 mentees since she started at the company 14 years ago. While on an eight-week assignment in Asia in 2008, Rich began mentoring a junior colleague in Jakarta, and the two have stayed in close touch ever since.

That’s not to say the time difference presents no challenges. “It’s nine hours later here than in Indonesia, so the best time for her to talk might be when I’m sitting down to dinner with my family — or she’ll send me a text at 3 a.m.,” Rich says. “But it’s not a problem. We both want to maintain the relationship, so we make adjustments.”

It helps that IBM, No. 5 on this year’s list of the Most Admired Companies, has built a culture of knowledge sharing, including a strong emphasis on mentoring. Since about 40% of Big Blue’s 426,000 employees worldwide are virtual or mobile — meaning they work from the road, or from one-or-two-person outposts where they rarely meet bosses or colleagues in person — the company has a wealth of experience with long-distance collaboration.

“If there’s a commitment from both parties, and a clear set of expectations, distance really becomes immaterial,” says Sheila Forte, IBM’s global chief of mentoring, based in Raleigh, N.C. and co-author of a book called Intelligent Mentoring: How IBM Creates Value through People, Knowledge, and Relationships. “In addition to our formal program, we encourage employees to seek out mentors and mentees anywhere in the world.”

Forte and Rich suggest four steps toward effective virtual mentoring:

1. Agree upfront on how often you’ll meet, and via what medium. “Decide between you whether you’ll have a formal session, say, monthly or quarterly,” says Forte. “Once that’s been agreed on, it’s up to the mentee to schedule those dates ahead of time. If you’re going to speak quarterly, set up those virtual meetings for the whole year ahead.” Not that you won’t sometimes reach out on the spur of the moment, she adds, but making appointments well in advance is “part of using your mentor’s time wisely.”

At the same time, Forte advises, “Agree on what form of communication you both want to use — email, IM, web cam, a combination? It sounds basic, but it’s especially important when you’re connecting across time zones.”

2. Tap into all the available technology. Nicki Rich and her mentee “started out scheduling meetings once a month, then went to once every quarter as her needs changed,” says Rich. “But I see her on Facebook every day. She posts a lot, both about what she’s doing at work and her personal interests, which really helps us stay in touch. We also tweet and text.”

3. Be specific and direct in asking for guidance. Once she gets to China, your mentor is going to be so busy that she probably won’t have time to figure out what you need help with, so articulating that is going to be your job. Rich has coached her Jakarta mentee on large questions (should the mentee accept a bigger job at a competing company?) and smaller ones (whose technical expertise should she seek out for a particular project?).

“She is very direct in asking me for exactly the information or insight she really needs at that moment,” says Rich. “That helps me give her my best answer.” Along the same lines, Forte adds, before each scheduled session, send your mentor an email description of any changes in your situation or other issues you want to discuss. “That way, you can get right into the substance of the discussion,” she says.

4. Follow through between meetings. First, after each conversation, “send a summary of what came out of the discussion, just to make sure nothing slipped through the cracks or was misunderstood,” Forte advises. “It’s always a good idea, but especially when great distances are involved.”

And second, says Rich, let your mentor know how her advice worked out. “I appreciate knowing whether what I suggested was successful, or less so. It’s valuable for me to know what works and what I need to rethink,” she says. “I learn a lot from hearing how a situation turned out. It really is a two-way street.”

Talkback: If you’ve ever had a virtual mentor — or been one — what worked for you? Leave a comment below.