Why not just dump the whole idea. It is bad, bad, bad. See blog below.
More Taxpayer Subsidies Will Not Correct Congress’ Medicare Drug Miscalculation: "The bottom line: Congress is considering paying companies to continue to cover something they already cover in order to deflect political heat from seniors who face the loss of trusted benefits. In other words, Congress made a mistake, and the taxpayers are now expected to pay for that mistake."