Hmm....
First step? Federalize Cisleithania along the lines of the existing kingdoms/borders, with a fair bit of local autonomy atop that. Border Gore To Create German Statelets, while popular with one set of nationalists, is likely to backfire; just insist that German remain the main 'federal/interstate' language of the civil service and insist there be full addressing-the-legislature/courts rights for the top two or three minority tongues in each area. Oh, and pass out noble titles to as many non-Germanophones & non-Catholics as possible.
"Oh, but with things going down that road, the 'minorities' in Hungary will grow restive!"
Well, yes. If they are pro-monarchist or at least willing to settle for the same deals the Galician Poles/Bohemian Czechs/Dalmatian Croats have, then the magnates in Buda-Pest have to explain why they must be denied.