In your command, SweetHome3D is probably a shell script. Open it with any text editor, and find the "exec" line. Mine starts with:More towards the end of the line, maybe several screen lines below, if your editor does auto linewrap, you find some parameters starting " -D...". Among these, surrounded by spaces but no hard line breaks of course, insert the additional parameter string.

My java knowledge is very limited, I don't even know if the sequence of parameters matters. But it won't hurt either.

HTH