How to flash boot partition on BBB?
Interesting, with the flasher image, all steps are shown how to partition and copy an image to the embedded flash memory:

Erasing: /dev/mmcblk1 complete
-----------------------------
Writing bootloader to [/dev/mmcblk1]
dd if=/opt/backup/uboot/MLO of=/dev/mmcblk1 count=1 seek=1 conv=notrunc bs=128k
-----------------------------
0+1 records in
0+1 records out
73516 bytes (74 kB) copied, 0.0287943 s, 2.6 MB/s
-----------------------------
dd if=/opt/backup/uboot/u-boot.img of=/dev/mmcblk1 count=2 seek=1 conv=notrunc bs=384k
-----------------------------
1+1 records in
1+1 records out
393496 bytes (393 kB) copied, 0.212742 s, 1.8 MB/s
-----------------------------
Formatting: /dev/mmcblk1
Checking that no[   46.657434]  mmcblk1: unknown partition table
-one is using this disk right now ...
OK

Disk /dev/mmcblk1: 119808 cylinders, 4 heads, 16[   46.673010]  mmcblk1: p1 p2
 sectors/track

sfdisk: ERROR: sector 3069486077 does not have an msdos signature
 /dev/mmcblk1: unrecognized partition table type
Old situation:
No partitions found
New situation:
Units = mebibytes of 1048576 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start   End    MiB    #blocks   Id  System
/dev/mmcblk1p1   *     1     96     96      98304    e  W95 FAT16 (LBA)
/dev/mmcblk1p2        97   3743   3647    3734528   83  Linux
/dev/mmcblk1p3         0      -      0          0    0  Empty
/dev/mmcblk1p4         0      -      0          0    0  Empty
Successfully wrote the new partition table

Re-reading the partition table ...

If you created or changed a DOS partition, /dev/foo7, say, then use dd(1)
to zero the first 512 bytes:  dd if=/dev/zero of=/dev/foo7 bs=512 count=1
(See fdisk(8).)
mkfs.vfat -F 16 /dev/mmcblk1p1 -n BEAGLEBONE
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mkfs.vfat 3.0.13 (30 Jun 2012)
-----------------------------
mkfs.ext4 /dev/mmcblk1p2 -L rootfs
-----------------------------
mke2fs 1.42.5 (29-Jul-2012)
ext2fs_check_if_mount: Can't check if filesystem is mounted due to missing mtab file while determining whether /dev/mmcblk1p2 is mounted.
Discarding device blocks: done
Filesystem label=rootfs
pm:Downloads pmu$ disutil list
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
233856 inodes, 933632 blocks
46681 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=956301312
29 block groups
32768 blocks per group, 32768 fragments per group
8064 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736

Allocating group tables: done
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done

-----------------------------
Formatting: /dev/mmcblk1 complete
-----------------------------
Copying: /dev/mmcblk0p1 -&gt; /dev/mmcblk1p1
rsync: /boot/uboot/ -&gt; /tmp/boot/
rsync: ignore the % values when shown as they are not accurate...
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
233856 inodes, 933632 blocks
46681 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=956301312
29 block groups
32768 blocks per group, 32768 fragments per group
8064 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736

Allocating group tables: done
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done

-----------------------------
Formatting: /dev/mmcblk1 complete
-----------------------------
Copying: /dev/mmcblk0p1 -&gt; /dev/mmcblk1p1
rsync: /boot/uboot/ -&gt; /tmp/boot/