That's the plan I will deliberately try to breed them but I am interested to know if it has been done before.
Plenty of bass keepers have big tanks but I have never seen or heard of Tems being bred.
I do at least know Tems aren't sexually mature until their three years of age. Than I would have to imagine you would need a huge tank / pond for them to spawn in. Couple of things you could do to help the process along is make sure the Temp is high at around 86 to 88 degrees and simulate a "rainy season" effect.. Like if your tems are in a pond, run a sprinkler close by that will rain down on your pond for a part of the day.
Yes it has been done. I used to have an article on it about 6 years ago. It was done in europe and I believe in asia. They do take several years to sexually mature and you must have a massive space for them to feel comfortable... Good luck.