If you know the path to the file you want to open then add it as an argument in a [loadmess] object. Otherwise maybe something like [opendialog] is what you're looking for.

Awesome, that helps a lot. I used opendialog to set the path name, but it's only going as far as to automatically prompt me with the correct folder, not the file itself, though I did specify it's full name.

If that's the case I can just number the files in order and open them according to that, but I feel there's probably a more automatic way. Can the preset object be used to recall filesets like this?

Have a look at [folder] and the "prefix" and "autopopulate" messages to [umenu] if you want to grab all the files in a certain directory. If you don't want to hardcode the filepath into the patch you could always save some of the data in a [coll] and refresh it using [loadbang] at startup.