OK, how about this:
A maga may, at any time, invest powers in the familiar bond. This is a laboratory activity, and the rules are based on those for investing a power in an invested device, with the following modifications.
There is no limit to the number of powers which may be invested in a familiar.
The maga gets no bonus to the Lab Total from other effects already invested in the familiar. Instead, she gets +5 if the effect matches either the Technique or Form used to bind the familiar, and +10 if it matches both.
Powers are limited to effects which target the maga, the familiar, or both.
The benefits of Verditius Mysteries do not add to the Lab Total. The Mystery has nothing to do with familiars.
If the enchantment affects only the maga, it is activated by and under the control of the familiar. If it affects only the familiar, it is activated by and under the control of the maga. This means that no effects in a familiar bond can use environmental triggers. For the use of effects enchanted into the familiar bond, the maga and familiar are always considered to be touching one another, and the bond touches both of them.
Foci that cover the familiar apply to the investment of all powers, no matter what they do. Foci that cover the power apply as normal.
Every time the magus invests a power in the bond both the magus and the familiar take on some minor characteristic of the other. This is a purely cosmetic effect, but should be stronger the more powerful the effect.
While this process does produce a Laboratory Text, that text only applies to investing the power into the bond of this magus and familiar, and thus is rarely of any use to anyone, including the magus who creates it.
One very important benefit of enchanting a power into the familiar bond is that the power does not cause Warping (page @@) as a constant mystical effect.
All other rules, such as level calculations, effect modifications, and vis costs, are the same as for investing a power in an invested device.