Lr-bsnes Super Game Boy on RetroPie?

[VultureStreet]

Hi all, I have managed to get full sgb emulation setup relatively easily through emulationstation on windows 10 using lr-bsnes in RetroArch. As this core is optionally available available in RetroPie I have been trying to get it to work but can't figure out how to edit the launch command. Is it even possible to do this or am I wasting my time?

EDIT:

To clarify what I mean, this is the entry in es_systems.cfg on windows which achieves this:
<system>
<name>sgb</name>
<fullname>Super Game Boy</fullname>
<path>C:\Users\Steve\EmulationStation\Games\sgb</path>
<extension>.zip </extension>
<command>C:\Users\Steve\EmulationStation\RetroArch\retroarch.exe -L C:\Users\Steve\EmulationStation\RetroArch\cores\bsnes_libretro.dll "C:\Users\Steve\EmulationStation\Games\sgb\Super Game Boy (Japan, USA).sfc" --subsystem sgb "%ROM_RAW%"</command>
<platform>sgb</platform>
<theme>sgb</theme>
</system>

I currently have a custom sgb setup on RetroPie that uses lr-mgba but I'm basically wondering/trying to change it to lr-bsnes. How/where do I edit the launch command on RetroPie to add the subsystem, etc?

Cheers