Not much to report as of yet, I'm afraid. You know, life and stuff...
I contacted Page Plus and received my MIN, MDN, and SID numbers. I also installed both Nokia Care Suite and DFS, neither of which I've used before. Nokia Care Suite appears, on first glance, to be more useful for full-on flashing and firmware recovery, but not necessarily tweaking specific settings. DFS appears to be better suited to tweaking the settings, but I haven't figured out how to specify the connected USB port in the connection manager, so DFS doesn't currently recognize my phone. I believe the next step for me is resolving the port issue, though I'm not sure yet how to approach this.
I also contacted a local Page Plus authorized dealer, who said initially that he wasn't capable of programming the Lumia 928 to Page Plus. He said he would call be back, but I have yet to hear from him. I may call him again to touch base.
Much of what I've read about (4G) Android and iPhone reprogramming for Page Plus suggests that the phone needs to be configured to prevent LTE use. Page Plus led me to believe that this is why the LTE phones cannot be programmed via the *228 method. So, it seems feasible that if I can configure this setting on the phone prior to activation, I may be able to allow the OTA programming.
Sorry for the lack of progress and spew of random thoughts. I only have about 1 hour per day to commit to this project, and that hour is pretty fragmented, which makes gaining any momentum a challenge. Luckily, I have a fully operational Trophy already working on Page Plus, so while I'd love to make the switch to the 928, I'm not totally starving to figure this out (yet). I'll keep in touch as I learn/do more!