How can I put a hot dog in a bun without splitting the bun? I have some store-bought, pre-slit hot dog buns. They are a little brittle, and if I open the slit wide enough to take the hot dog, the bun splits in two.

I've tried using my toaster oven to warm the buns. They taste nice that way, but it they don't soften much.

Any other tricks?
Steaming them will soften them up for your dogs. The quick-and-easy way to do that would be to microwave (as another user suggested), or just over a pot of water briefly until they're soft enough