Use the new Create Custom Geographic Transformations tool in ArcToolbox to define the transformation. The result is saved in the .gtf file in <a href="file:C:/Documents" target="_blank">C:\Documents</a> and Settings\<login>\Application Data\ESRI\ArcToolbox\CustomTransformations. This file can be moved between machines, but needs to be placed in the same relative location (under the user's login).