If you have a large enough team, then you have at least one person (and likely more people as your team is larger) on that team with is an architect personality type. Many tend to migrate to IT areas. This will be the people who designs your IT systems, who can tell you how to structure your load balancer and your networks and your firewalls and your servers to get the most out of your applications.
On the development side, they're likely to be a lead developer who always seems to be planning ahead for their team in terms of tools and structure. On the infrastructure/server side they're the guy always automating stuff and creating systems that run themselves.
This is 5% of the population, max. Maybe closer to 1-2%. But even if you only have 50 IT guys, that gives you good odds of one or more. You're looking for the people who are the ones always automating stuff and creating not only new IT systems, but new process systems for how people do stuff and making suggestions on existing systems for how to make them better.
One of those guys in each of the major IT areas of your company is who you want to look for. They'll already have an understanding of how the "people" systems in that IT area works. They haven't told you how to make it better yet because their past experience is that management has their own ideas and typically doesn't care for theirs, or ends up poorly implementing theirs. They may not believe you at first when you tell them you want them to give you a plan on how to improve things. Don't take no for an answer. Tell them you'll most likely do whatever they say, they just have to outline it for you and help create the details.
Tell them you just want them to improve the end results of their IT department, whatever that is. It's typically something like the service the customer receives, or depending on your company, maybe internal customers instead. You don't need to go into different effort levels by people. They know all that. You aren't really looking to improve person X's work ethic with incentives, right? You really just want better overall results. Focus on that goal.
They won't be able to resist. They'll design something for you. If they are less experienced in the workplace, it may take a couple of iterations as they figure out how people respond. Bring up the individualization options so that they don't focus on a one-size-fits-all option. Make sure they understand the option to throw out existing process requirements, not just add new ones. Those might be blind-spots for them otherwise.
Asking for ideas/feedback in a group meeting isn't going to work. These guys will have enough experience to know that they could only at best suggest an incremental improvement to what you already have. Anything more than that and it's going to get screwed up in the implementation details. No, give someone individual responsibility for creating an entire system framework for improving your desired overall goal, then stand back and watch the ultimate results. You'll be surprised at how well they know the business of what their IT department already does and how to improve it. You'll be shocked at how much pointless waste and inefficiency you have that can be gotten rid of.
Or, if you really don't think you have someone who can do that in your group, then feel free to hire someone like me to come in and interview people to get the same answers and put something together for you, but that costs more money than an Ask Slashdot. :)