Is it possible to add pushbuttons to the SAP Easy Access Front Screen when a person logs in? 
This is the SAPLSMTR_NAVIGATION screen no 100. This is the first screen you typically log onto and I want to add a pushbutton (and we are not showing the standard SAP picture on the front screen). Although I have put a button on here, it does not show within the image container although I can show this at the bottom of the page. Is this possible using GuiXT as we would like to make a user entry point with several buttons for people to start from (like favourites)?
Yes, this is possible. Some companies have even added a mulit-level menu here, using a status variable like V[menustate] to allow navigation through multiple menu levels. We can send you an example if you are interested.

Please shift the SAP easy access menu downwards, e.g. with

pos [IMAGE_CONTAINER] (12,0)

or to the right:

pos [IMAGE_CONTAINER] (0,32)

to get enough space for your own menu.