Paragon multiclassing occurs instead of a PP
You must take the three multiclass powerswap feats and then choose Paragon multiclassing in lieu of your PP to be eligible for Sorcerous power. The only instance that I've seen where this is remotely useful compared with just taking a hybrid is with a warlock MC Swordmage for aegis.
As a means of optimization, actually, it's not bad. As a genasi, you would be able to add strength twice to the wizard arc lightning. While this is competing with wind-rider, 2xStr is... comparable to any PP damage booster out there, providing that we can find a daily, an encounter, and a utility that are not sacrifices.
- Level 15 lightning daggers is very very attractive. And before that howling hurricane is quite nice. While there are some excellent level 9 dailies for wizzies, there are no "must take lightning" ones.
- Lightning cuts is excellent as a minor action attack, since you'll be going with a dagger as implement anyways (to get the correct superior implement) and my choice over shock sphere which I've always found to be tetchy with positioning.
- There are an incredible number of sorcerer utilites that are purely awesome. Any of the elemental ones for flavour, especially if you take wild talent master and psionic spark and fire stride (and all the firestarting that entails) or sudden scales or etc... Sorcerers have fantastic utilities.
Now, the MAD is going to hurt (which is why I generally have lightning blasters go wind-rider) because you'll want 16 str, 16 int (pre-racial, like a starting sorcerer build) with enough charisma to hit. Still, it's quite viable and rather optimized.