With Mac osx 10.4.x and the 4000 you need to go into the printer setup utility, thisd will list the installed printers if only one occurance of the 4000 is there check the kind and if it is the CUPS driver then you will need to click on add printers, when the add printers window opens you need to click on the more printers button, when the more printers window opens you need to select the connectivity ie EPSON USB or EPSON Firewire depending how you printer is connected.
When the printer appears in the window highlight it and at the bottom of the window under page setup from the dropdown menu select the ALL option from near the top of the list. This will install a number of instances of the 4000 printer with differing paper source settings.
For the Pro4800 the paper source is selected for the standard paper sizes in the page setup menu, the various paper sizes have pop out menus that allows the selecting of the paper feeds and borderless options. For custom page sizes the determination of the paper source is dependent on the margin set up with 3mm margins set all round it defaults to roll paper, with any other values in the margins it defaults to cut sheet. (this is a bit genuralised).