With Max 7, it is quite simple. Start up Max. Go to Customize, select configure paths from the dropdown, go to the Plugins tab, click Add and browse to the directory where the messiahMAX6x.dlm resides (usually …\pmg\messiahstudio or messiahanimate\messiah). Shutdown Max, then start it up again. Now Max should have found the plugin alllowing it to communicate with messiah.
Now go to Customize, select Units setup, then System unit setup. Make the system unit scale .01 meters. That way, Max and Messiah’ll be thinking in the same ‘size’.
In the right pane, go to utilities (the hammer thingy), click on More…, find and doubleclick messiah Util. Now click Launch GUI. Now messiah’s started up.
Load any messiah scene file, or project or object into messiah. With scene-files (maybe projects to, haven’t tested that yet), messiah asks you whether you would like to link the objects to max. Simply flag the ones you want and click ok. Alternatively, you can at any time select an object and click F12.
Now go back to Max. Under messiah Utils, there’s an area marked Object Import, which’ll say x objects on deck (x being the number of objects you linked up from messiah). Simply click IMPORT, and there they are, animated exactly as they are in messiah.