I wonder if it would be feasible to create a pool of group powers for something like this. This is only a preliminary idea, bear in mind. You could have each character dedicate a number of his refresh to the pool, and then you buy powers for that pool. Each character can then draw powers from the pool by the predefined condition, in this case the chronomancer casting on them. You can only draw powers equal or less than the number of powers you dedicated to the pool.
Eh... I just realized, that's modular abilities with attached human form (or magical enhancement or limitations) and some restrictions on what powers you can take.
That would probably take care of most of the speeding up needs you have. You could even have a character with inhuman speed and 2 modular points upgrade to supernatural speed.
Unless the sped up workshop is relevant to the game, it doesn't really need any powers or spells attached. Maybe as part of the chronomancers aspects, but not much more.