Well the minimum you need is a PC with a floppy drive, the disk images and software to write them to disk.
If you don't have other old PCs and provided that you have a way of transferring files to the jr, you can even use that to write the images.
You just need software that works on the jr, I'd put my money on ImageDisk by Dave Dunfield or DskImage by M. Brutman.

Keep in mind that disk images for booters not always come in the standard .img raw file that the above programs can write. Some have been made using Teledisk to preserve more data about the image and I don't know if Teledisk can run on the jr. I'd also bet that some cannot even be written back using a normal pc floppy controller, but don't worry too much about them they probably are only a handful of titles.

Dskimage works great for me.

thepirategamerboy12 wrote on 2022-01-31, 01:02:

Dskimage works great for me.

Great I’ve been trying to use imagedisk. Is there a specific disk image format you use when writing to a disk? I have a 486 with a 360k drive I’m using to write to disk.

theoakwoody wrote on 2022-01-31, 04:38:

thepirategamerboy12 wrote on 2022-01-31, 01:02:

Dskimage works great for me.

Great I’ve been trying to use imagedisk. Is there a specific disk image format you use when writing to a disk? I have a 486 with a 360k drive I’m using to write to disk.

To write a 360k .IMG floppy image to an actual disk, type: dskimage filenamehere.img 0:40:2:9. Replace that 0 in the beginning with a 1 if the 360k drive is drive B:. You can also swap the positions of the filename and floppy drive sections of the command to make images of 360k disks.