As for the Xserver requirement try out Xvfb it allows you to run a virtualized (fake) Xserver to eat the windows created by java or other X apps that really don't need interaction. The link above has instructions on how to set it up. As for editing the powerpoint file directly the specs are not well documented and MS tends to toss in weird behaviors in their file formats to make it hard to directly edit them -- so I would avoid doing so if you can.