i don't think you can gget there just using already made objects tbh.
maybe if you hack a
string inlet into the
jt/midi/play module you can achieve what you want? you would still have to take care of the looping part, or converting to a axo table.
tbh i think the best solution would be to avoid midi files and use axoloti tables instead that you just read/write from sd card. array of 16 or 32 int32, you can then either write a midi converter or just use the several table editors/sel modules to create and save your own sequences. then cycle through them with a table load module.
like this, reading your arp steps from tables named "arp001.tbl" to "arpXXX.tbl"
now you just have to write those table to disk with another patch...
if you have to use midi files, i think there's no way around coding your own objects, hacking on top of johannes midi file parser.