Additional buttons in button editor on Source and Record monitors

Hey there-

I'm an editor full time and have finally taken a project on Adobe Premiere after working on Avid and at times FCP for the last 12 years.  I'm pretty sure I know the answer already, but is there a way to add more buttons to the button options in the button editor on the source and record monitors?  Seems like this is a pretty basic feature that a lot of people would probably want for customizing their setup and unfortunately I think that the buttons provided in the button edtior are all Premiere users are given to work with for customizing.  Thanks.