Load the MLO and U-BOOT in beaglebone black through USB port

How we can load the MLO and U-BOOT in beaglebone black through USB port? I know it can be done by SD card/serial and it will load to eMMC but if I have a ‘USB stick/External HDD/USB connected to a host PC’, how can MLO and UBOOT be fetched through USB port and transferred directly to eMMC.

Once there are done and we get the UBOOT prompt, we can surely upload the kernel image etcfrom any known interface available.