PI_Target

This addon offers an easy Power Infusion assignment macro.  Simply right click who you want to set as your Power Infusion target, select the option with their name, and it's all set.  This addon will generate/update a macro named "PI_Target" in your general tab with the given players name inserted into it.  It will then scan your bars and if the macro is not currently equipped, it will place it on your cursor for you to put where you want on you action bars.  A note of caution, macros can not be changed in combat, so if you attempt to change it in combat, it will display a message in chat saying it is unable to do so.

For the advanced users, in your addon options, or you can type /pit /PIT, you can specify exactly what you want the macro to do.  I have a default template that you can modify.  Instructions on how to make it create properly are underneath the text box.  I included color coding so you can know if you entered the template name correctly.  After saving your custom macro template, you must reassign your Power Infusion target for it to use the updated macro template.  All settings and macros are character specific.