How to safely home pressure can plain jalapeno peppers using the tested USDA method.
Do not do larger jars.
It is one thing as a cook to brave prepping one or two jalapenos with bare hands; it is a different thing altogether to prepare them in industrial quantities. Wear gloves, or your hands will go dry and burn for hours on end, even with mild Jalapeno peppers. (Sweet peppers are fine.)
The seeds are where the heat are; you can leave some in, if you wish.