What is the "easy" way to copy files into a hard disc image ?.
easiest way for me is to use XM6 emulator - load the hdd image (or images) and transfer files that way.
Use this (https://hp.vector.co.jp/authors/VA013937/editdisk/index_e.html) to open the image and just drag and drop files into it. Can't be easier.
Just be careful when using Disk explorer, it can cause file corruption. If it does corrupt a file constantly you can try compressing it first, moving over with disk explorer and then unpacking it in LHES
I created a second, smaller (10MB) disk image on my BlueSCSI and copy files to it using Disk Explorer on my PC. After, I copy the files from that to my regular HDD image on the actual machine. That prevents any possibility of corrupting the disk I actually care about.