Hi, for the new way you don’t need any special tools except HDInstTools (recommended) or HDToolBox (has trouble with big disks).
Insert a USB stick in ZZ9000 and then turn on your Amiga.
Then, go to Icon Information on the HDInstTools icon and enter zzusb.device as the Device in Tool Types.
Next, start HDInstTools. It should discover the USB device as a harddisk. You can then partition it as usual. Make sure to use FFS, or if you want to use another filesystem you will have to mount the partitions manually after boot (using a tool like GiggleDisk / a Mountlist). If you use FFS, keep your partitions below 4GB. Then, save to disk and reboot. If everything goes well, you should be able to see the partitions and format them.
You can then access the partitions on another computer. Linux has native support for RDB and Amiga OFS/FFS, so you can just mount the partitions like mount -t affs /dev/sda1 /mnt. On Windows/Mac, I think you have to use UAE and allow it to use the whole USB stick device as a raw disk.