You can’t. The BYOD (Bring Your Own Device) movement is simply a continuation of the same life cycle that happened with cell phones.
At my first job with Exxon in the early 90’s, it was the important people who had a company phone. The phone they received was the old Motorola 8000X brick phone, which to us was very cool. Fast forward to my first pharmaceutical job at Bayer and it was still the company elite who had cell phones but they were getting much smaller and more useful. By the time I started Skura in the mid 90’s, we decided to equip every employee with a walkie-talkie/mobile phone combo. As the price point dropped and feature set grew of these phones though, the consumer market changed the dynamics. Fast forward to today and almost everyone has their own cell phone from my Mom and Dad living in Key West to my 12 year old daughter texting friends and using Facebook. Another interesting trend is that kids don’t talk on the phone anymore, they type, more on that later though. You don’t decide what phone your employees own: you can go out and buy them an extra one if you have money to burn but other than Facebook and Microsoft I don’t think many companies are in that position.
The same thing will happen and is happening with tablet devices. Your employees are out buying their own device now. A time will come soon, where most of them already own a device they can use in the field and your choice as an organization will be whether you want to buy them an extra one or not. You can be like the company who just bought 14,000 iPads without knowing first what they would be used for (http://www.cultofmac.com/184246/how-one-company-made-a-multi-million-dollar-blunder-in-buying-14000-ipads/) or you can find a way to leverage the wave that is already happening and bring your organization to the next level.