How do I correctly upload a music replacement mod to Steam?

[karmic idol]

I have tried to upload several music mods to Steam, but from the few comments I've got it seems that these mods don't work. I know that the music mods work on my end, and I used the same method Solaris described in some Steam forums for how to replace Serious Sam music (recreate file path from the main gro in the content folder, add in custom music). How do I use the Serious editor to create the gro file correctly and then upload it to steam? or is there a different way I should do this since I am exclusively modifying music files for pre-existing levels?

[rose pulsar]

Do you have .gro file with your music, which replacing original?

[karmic idol]

I turned my file from a .zip to a .gro file manually, mainly because I couldn't figure out how to use the create a .gro in the editor to convert the zip file.