Drugmaker Alkermes' (ALKS) acquisition last year of Elan Drug Technologies was a masterstroke for the company, and institutions are reacting the way you'd expect -- they're buying. As soon as the ink dried on the billion-dollar buy, Alkermes cut its tax liabilities. How? By moving its base from Waltham, Mass. (which is still home to its R&D center) to Dublin, Ireland. You may not think of Western Europe as a low-tax alternative, but Ireland makes