To help the Torsen, you want to increase the inside rear tire load on corner exit (or reduce the overall unloading in a corner), or increase the speed at which the load transfer takes place. You can decrease the inside rear unloading by either reducing the rear roll stiffness or increasing the front roll stiffness. You can affect the rate of load transfer with low-speed shock adjustments. But shock adjustments only work on shocks that are moving - a shock that's not moving develops no force for the suspension.
As the car transitions from steady-state corner at the apex to power-on exit, the suspension movement is going from roll to squat. The outside front corner is losing load / coming up / in rebound, and the inside rear is gaining load / moving down / in compression. To increase the speed of that load transfer, you want to increase the compression stiffness of the rear shock, and/or decrease the the rebound stiffness of the front shock. These same adjustments promote understeer on corner exit, which helps counter the oversteer being induced by a RWD car's increased longitudinal grip use of the rear tires under acceleration.
So both the sway bars (and springs) and shocks can change the percentage each axle sees of the total lateral load transfer, which then tunes handling. But the bars & springs change it for all phases of a corner, whereas shock adjustments can change it for specific phases of a corner.
This has a good explanation and a chart of shock adjustments -
http://www.ozebiz.com.au/racetech/theory/shocktune1.html
Note that the same shock adjustment can affect the car's handling differently in different phases of a corner.
For different surfaces, the easy assumption is that you're changing the maximum grip level, so you can attain more lateral & longitudinal g-loading. The same adjustments apply, just with more grip they have more affect - as more load is being transferred, any difference in the load transfer percentage front-to-rear will be more pronounced. Bumpy vs. smooth is a whole different matter, where you can work with high-speed damping, but for very bumpy you want to make sure your rebound/compression split is not so great that you "jack down" or "jack up" the shock - soften all-around to let the shock find it's balance more easily.