如何使用tabview1上的按钮切换到iOS iPhone tabview2

I've read some internet posts that nearly answer my question, but I cannot put the pieces together. I have a two-tab iPhone app, with the two associated view controllers, h, m, xibs et al. There's a button on tabview1 by which I want to switch programmatically to tabview2. I've read discussions about setting up a root view controller to manage this, but the examples just haven't carried enough detail for me to figure it out, and appear to suggest that I change over to a nav-based app, which I really don't want to do. Anyone have the patience to explain it to me?I've read some internet posts that nearly answe