I’ve edited the previous post on the house rule to remove any randomness from the requirements.  You can reference the original post for the updates, in short, all rolls are removed, and the required training hours is calculated as such:

(100 hours for basic skills, 150 for advanced skills and talents) + (50 hours if the skill is outside your current advance scheme) – (applicable stat, in hours)

For example, read/write for someone who doesn’t have it in their advance scheme, with an int of 40 would be:

150 + 50 – 40 = 160 hours.