yes, in principle you can do that but in practice, there is just not enough leeway between the bottom bracket shell and the gearbox's case to do that. I filed down my cableguide to just 3mm high, remove the bolt and spent half an hour fiddling with the motor to keep the gear cables in place. If you have a 3D printer, it may be possible to make your own low profile cableguide but it's just not worth the effort compared to running a new derailleur cable from shifter to derailleur.
In most cases, you won't need the front derailleur so there is only one cable to worry about.