After reading through everything, I would have to answer this question with a resounding "NO!" And here is why I say that:
1) pg. 66 -
QUOTE
Note that for most metatypes, the maximum rating for Magic, Resonance, and Edge is 6; humans have a maximum Edge rating of 7. Certain qualities (Lucky, Exceptional Attribute) allow characters to exceed attribute maximums by one, but the player must purchase these qualities with Karma and may only do so with gamemaster approval (the player may purchase either Lucky or Exceptional Attribute, but not both).
2) pg. 98 in the table listing what you can spend your karma on - nothing is listed for initiation and in the text nothing is listed for it either. It does refer you to the "Character Advancement" section, but specifically for attributes and skills purchases.
QUOTE
When spending Karma for attributes or skills, refer to the rules for improving the character in the Character Advancement section (p. 103).
However... if I were to run a Prime Runner campaign, then this would all change. I don't know too many mages that I would consider Prime Runners that have not initiated, so for that particular campaign I would allow it because you are building an experienced runner at that point. But for Street or Standard, it will be a big no.