Today, some one posted in MSDN forums a question regarding, opening the pre defined document library in an Explorer mode from the custom WebPart.
Option, which is available with the ribbon menu of the library.
This can be achieved using below, by using the NavigateHttpFolder function in the core.js
This method takes hex encoded URL and frameTarget as the parameters.
It worked for SharePoint 2010 and MOSS 2007 in IE8 and Firefox browsers.