It's not based on the 4e rules, but coincidentally in the latest post in my "30 Dimons for November" project I suggest some alternate rules for awakening crafted items with hermetic magic:
The general idea is that the item can be taught abilities for a period as if it was a being with no might, but it must be fed vis every season to keep it stable while you do so. During this period the magus can also try and influence the traits and powers of the awakened item. Might be of some interest.
For using the old rules it's tricky because of pyramid scales. 25xp is probably the closest direct conversion, just under a score of 3 if starting from 0, that's what I would go with to get the same feel as how it worked in 4e.