Your word choice was good. This is primarily a development process. By definition it's not quick. The best companies at developing a well-stocked leadership pool, such as GE and Caterpillar, seem to do the same things.
They hire carefully. They tend to look for specific patterns, and draw graduates from the same kinds of schools. For years, for example, Sonoco used to look for young men from small southern towns who had either a poor start at college, or who took some time off and then suddenly improved performance.
They provide a rich training environment in all the key areas. Key areas include culture, technical skills and management/leadership skills.
That's pretty straightforward, but the fact is that there are almost no simple predictors of business success. So most of the companies who've developed rich leadership pools do a few other things.
The best companies pay attention to leadership development. That means constant review and feedback coupled with challenging assignments. That's where the high potential folks prove their worth.
Top companies also provide lots of good role models and encourage senior executives to mentor junior managers. Great leaders don't learn their trade from books. Leadership is an apprentice trade, learned mostly on the job from master practitioners.