The STM8FLASH installation instruction on GitHub are best described as "you know how to read a Makefile and learn from the error output, don't you?".

I now described the (simple) steps for installing and testing stm8flash with a bit more detail.

There are also updated instructions for resetting a read-protected STM8 µC (some manufacturers of STM8SF103F3P6 demo boards think it's wise to protect their "intellectual property" in "blinking LED algorithms" by setting the Flash protection option bits).