There are slightly different methods for some Epson printers to do this, but here is a "quick'n'dirty" method that will work on them all. It is quite safe and will not damage the printer.
Switch the printer on. Press and hold the "head clean" switch. When the head starts to move, pull the mains plug out of the printer. You can now easily slide the head assembly gently to the correct position and change the cartridge. After changing the cartridge, simply connect the power lead and switch on. The head will return and a recharge sequence will be executed, then away you go as normal.