Useful summaries, thanks!
A few points specific to what I'm doing:
- The final tool must work on Mac. If it works on Windows/Linux that's great, but that would be for broader distribution. The primary need is to run on some of the Macs here at university, some in rooms where I teach (reason: to help my students learn about and prepare print projects) and some in the open-access digital print facilities (reason: to reduce the headaches my colleagues there have with poorly-made student PDFs). Solving cross-platform complexities is a good aim but it should be a stage 2 thing.
- Getting admin-level installations done on most of these Macs would be, ah, 'rather difficult'... they're centrally managed, and while the 'local' IT department is very favourably inclined to me and my shenanigans, the central team is much more of the 'not invented here' mindset. (For a tool distributed more publicly that's fine, but that too is more of a second-stage goal.) Hence me wanting to internalise or localise the *TeX 'installation' as something that is used entirely on the fly. Which leads me to...
You said "installed properly" and "as long as the $PATH has been updated during installation."
What I'm trying to figure out is can something like this be 'installed' by (a) having it available in a logical place (even, dare I think it, inside an app package?), and (b) setting up $PATH appropriately – even if it's just for the duration and use of the shell that does that?