Ok, so I have put the modified scripts on a KoboRoot.tgz, as promised. This would only work if pbchess was installed inside the .kobo folder. If it is installed elsewhere, the pertinent paths of the files and the scripts should be modified to make this work.
As always, one should unzip the CoolReader icon into the memory of the device, unplug it from the computer and let nickel scan it. Then, plug it again, unzip the KoboRoot.zip file and put the resulting KoboRoot.tgz into the .kobo folder.
The icon was designed by @whatsapps and uploaded to
steemit.com. Any other image would work as long as it is named 'CoolReader.png'.