4.3U means nothing if running the loader
The loader runs on an ios above 200, in these slots you can install modified ios's to allow the loader to run, the slot number means nothing, it is what is installed
250 - d2x-8final(57)
This means in slot 250 - d2xv8 final code is used to modify (57 - nintendo's 57 ios)
They can be installed anywhere if you know what you are doing. Modmii is great it is easy and as a standard installation installs
Hermes special code
222 - Base 38
223 - Base 37 merged 38
224 - Base 57
d2x special code
249 - Base 56
250 - Base 57
So the game needing base 57 should run on either 224 or 250
But this depends on the guide you used.