This kinda thing really gets on my wick. Sometimes a plugin comes along which doesn't source it's own shelves. When that happens you have to hunt around in the file system to load the shelf. So instead popping this file into the scripts directory of the p

userSetup.py

import maya

def bbLoadShelf(name, filepath=""):
    mainShelfLayout = maya.mel.eval('global string $gShelfTopLevel; string $tmp=$gShelfTopLevel;')
    labels = maya.cmds.tabLayout(mainShelfLayout, query=True, tabLabel=True)
    if not name in labels:
        maya.mel.eval('addNewShelfTab "%s"' % name)

maya.utils.executeDeferred( bbLoadShelf('MyPlugin')