its pretty hard to find now a days
your best luck is looking for the 1866 mod im pretty sure that it comes with that mod
or digging through the modb site or even the old mount and blade forum

https://forums.taleworlds.com/index.php?threads/mount-blade-iron-launcher-1-3-1-by-swyter.67313/

link to taleworlds forum about the iron launcher