Yes you can with jdflasher and for greek you find firmware with this :
MEDITERR - English - Bulgarian - Greek - Macedonian - Romanian - Albanian
MAIN - W580_R8BE001_MAIN_GENERIC_LA_RED53
FS - W580_R8BE001_FS_MEDITERR_RED53 and
CUSTPACK - HB1-06_Gen_CDA102568_4_R8A_GENERIC_MEDITERR
And use this tutorial Flashing with jdflasher - Top Sony Forums