Okay, I figure I owe the rest of the board an update
It took CoBB and me about a dozen private messages and a lot of patience to find out that the linux non-interactive build that's on the PTI website is actually broken. It'll never turn the screen on. Once that was clear I tried to recompile a new version of the linux non-interactive build from the original source, but that gave me exactely the same result. So that pretty much got me nowhere. Now I'm just hoping that CoBB will come up with a brilliant idea.
But I've been using the Windows version in non-interactive mode through Wine (talking about an ugly hack

) to develop my front-end, and it's getting together. Here's a screenshot of the first "Mem cleared"
It emulates a screen, with more or less as pretty looks as the original (though I still have to properly fix an ugly signed/unsigned int error, what you're seeing here is the yucky workaround). It updates the screen 25 times a second, which is the maximum greyscale output frequency of the PTI back-end, and it has the emulator run the corresponding number of clockcycles on every update. In other words; you can see the cursor flashing at the proper speed
Interface-wise you can load a ROM image and .8?? files through a fancy file browse interface (Emulator -> Open -> "ROM image" or "Program/Group", can't take a screenshot of that for some reason, so you'll have to take my word for it), you can make the program dump it's status to the command line and you can type in keys which will be passed on to PTI. I still have to add a few more keys though to make it useful
It depends on libgtkmm and it should run nicely under Gnome and KDE.
Now the only serious problem is to get a native Linux build that works properly...

Otherwise this little program doesn't really solve any problem...