Last northern spring, Scott Heintzeman, CIO of Carlson Marketing, and his staff were developing new business intelligence systems. The project would support Carlson's marketing business unit 1to1, which helps clients mine their customer data to create individualized direct-marketing materials. Carlson executives expected the business unit - a new line of business within the company - to be one of its top performers. Heintzeman knew he had to deliver, but he couldn't do it on his own.

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• Situations in which CIOs must influence colleagues
• Strategies for persuasion

Heintzeman was not worried about the technology needed to support the unit. He was more concerned that 1to1 lacked a strong business leader - someone aggressive enough to establish business processes and rack up some quick wins, while personable enough to help employees through the inherent stress and uncertainty of a new venture. Heintzeman believed he knew someone who was right for the job: Janet Sparkman, the general manager of Carlson's Gold Points Reward Network, a customer loyalty program that is one of Carlson's core businesses. Heintzeman had worked with Sparkman previously and they worked well together. So he asked Sparkman to consider a job change. She flatly declined.

That's when Heintzeman went to work, lining up support for his plan among other business leaders and assembling a dream team within IT to support Sparkman. He knew what attracted Sparkman to new ventures: "Janet isn't going to join something that she cannot win," Heintzeman says. "No way would she make that change if she did not have the right IT team to support her."

Heintzeman's initiative to weigh in on a strategic business issue is familiar to any executive but particularly challenging for CIOs, who have little formal power, observes Susan Cramm, a former CIO of Taco Bell who is now an executive coach (and a CIO columnist). Often, a CIO's impact comes down to how good she is at convincing business leaders and end users - who don't have to listen to her - to follow a strategy that the CIO deems important. "The ability to 'lead from the back' becomes essential for success," says Cramm. "Without influence skills, CIOs are relegated to being order takers."

To have influence, it's not enough to be able to explain IT in an easy-to-understand way. To sway opinions and convince others to act, CIOs need expert knowledge of their subject and its relationship to the business, the ability to adapt their message to how their audiences like to learn, access to allies who will support their goal and the ability to vet ideas in a non-threatening way.

We interviewed four CIOs who employ these and other techniques to influence the strategic direction of their companies. Their influence is directed toward a variety of goals. These include - in addition to Heintzeman's effort to persuade an executive colleague to change jobs - redirecting an outsourcing strategy, persuading a senior executive to make a major IT investment and selling new technology to sceptical end users. Having influence requires developing relationships that are based on trust so that you gain allies inside and outside the IT department to vouch for you. "CIOs need to make sure they are investing in relationships all the time, because one day you will have to take a withdrawal," Cramm says. "If you wait until something happens that requires you to rely on someone, [and] you don't have any [capital] to withdraw from, you won't be able to influence anything."