Make microwave popcorn in the oven
I'll come out and say "no, you can't make microwave popcorn in a conventional oven."

For popcorn to pop, the kernel must reach a temperature well above boiling (which builds up steam, causing the kernel to explode). It must do so very quickly, otherwise the moisture will just slowly evaporate out, simply drying the kernel rather than popping it.

Microwave popcorn works because the microwave is primarily heating the kernels directly (because they contain the most water), and quickly. Air poppers don't use the oil, but they do get very hot, and the forced air heats the kernels very fast. And stovetop methods use the heat built up in the oil to heat the kernels quickly. Even fire-popped corn (a fun prospect) relies on fast heat.

Unfortunately, ovens are anything but fast. In the time it would take to heat the kernels, they would just dry out, and possibly start to burn the bag.

If you want popcorn without a microwave, stovetop popcorn is quite easy, and very tasty. I like using a wok, because it's shape is well suited for popcorn (sloped sides keep the kernels in the hot spot, while allowing popped kernels space to expand).