I believe they have a converter on their site you can use to convert the fusee-primary.bin file in Atmosphere's 0.8.4 release in the meantime.
Hi again! Draxzelex, the converter they have on the site is an XCI2NSP, nothing related to payloads.
Now that sigpatches are out and running, I guess they´ll be updating the r4 software soon...
Anyway, just for learning and curiosity, what should I search to find this kind of fusee-primary converter?
Thanks