Installing Koreader using the latest nightly build on GitHub has a serious issue on Kobo Mini - there is no way to exit into native system (I had to take apart my device and manually delete Koreader files from microSD card.)
To solve this problem I've created a simple install pack based on Markismus's excellent 1-Step-Hack. It contains the latest Koreader and CoolReader builds, and it installs and works fine on my Kobo Mini with firmware 2.6.1. After the first install updating to newer versions must be simple using the recent official Koreader an Coolreader (pbchess) install files. I hope it works on other Kobo devices too.
Install files:
AltReader_CR1.2.6.3_KO529 (BE CAUTIOUS, IT'S TESTED ON KOBO MINI FW 2.6.1 ONLY!)