You normally access shortcut properties through the right-click menu, but when you're dealing with a Windows 7 pinned taskbar button, that's just going to pull up the excellent Jump List feature. So how do you customise the shortcut?
Over at Windows expert Paul Thurrott's website, he points out that you can easily access the shortcut properties for a pinned shortcut by first right-clicking on the taskbar button, and then right-clicking on the name of the application in the Jump List, which will let you easily access the properties dialog. This is especially helpful for custom shortcuts like pinned Google Chrome Application windows, which are difficult to access otherwise, but it should work for any pinned shortcut.
It's a very simple tip, but useful if you wanted to customise a shortcut to add extra command-line parameters, start maximised, set the compatibility mode, or even set it to run as administrator by default.
Customize Pinned Taskbar Shortcuts [SuperSite for Windows]