cura and slic3r can be set up to send the gcode directly to gpx.
It's actually exactly what simplify3d does.
Although I never got it to work with slic3r - others have.
I did read there was a plugin for cura - but could never find it.

You need the correct settings in the gpx ini file as well as the right start and end gcode.

There's a thead with the whole setup process in - I couldn't get it to work. But it was probably me ;-)