I did a little bit more digging myself and found this file, which contains the command used to launch ScummVM:

/usr/lib/python2.7/site-packages/configgen/generators/scummvm/scummvmGenerator.py

I managed to do what I want by adding "-b", "1120" to the commandArray defined on line 38.

What would be required to add this into the UI? It would make most sense to configure it per-game, if possible.

It is possible to pass a command line argument -b BOOTPARAM to ScummVM, which can be used to start the game at a different point.

https://wiki.scummvm.org/index.php/Boot_Params

Is it possible to configure the emulator in RecalBox to pass this argument?