You must split the value into four 16-bit values and print them separate:
unsigned long long val = 0x1234567890123456ULL;
printf("0x%04x %04x %04x %04x\n",
(unsigned)(val >> 48ULL) & 0xFFFF,
(unsigned)(val >> 32ULL) & 0xFFFF,
(unsigned)(val >> 16) & 0xFFFF,
(unsigned)val & 0xFFFF);