As you know from the SQH Discord, I've been trying this out using other methods... and just for reference here:

• the /KEYB switch in the readme doesn't make a difference
• the up arrow doesn't work in real DOS either
• configuring the game to joystick mode does allow passing the teleporter, but only once and after that, I had to restart the game to get it to work just once again

Having checked the old version in STORM1A.ZIP at https://www.dosgames.com/forum/viewtopic.php?t=18422, which does work correctly, I found that the old version's keyboard IRQ handler is completely different. The new version (4.0) just uses an array of bytes, indexes it using the scancode, and ORs the byte to 1. The old version (2.02d) explicitly checks a whole bunch of scancodes right there in the IRQ handler, including scancode 48h for the up arrow.

After unpacking the executables, I've found:

• IRQ handlers at file offset CFC6 (old) and CE0D (new)
• code that checks for the teleporter activation at F33E (old) and EEE4 (new).
• it checks for DS:9724=0000 DS:9744=01 (old) and DS:76A2=0000 DS:A2EA=01 (new), and writing those values to those memory locations with the DOSBox debugger triggers the transporter in both
• the IRQ handler in the old version writes those variables directly, in the new version there's code that writes them at file offset C1DD - but this appears to not be executed

If anyone else sees this with the same problem, V2.02D of the shareware episode works without the teleporter bug, and as it turns out is the version included with the Registered version.