See the full readme in the parent directory.

quick howto:

from the readme:

   dBUG> show
   ...
      server: 192.168.16.100
      client: 192.168.16.101
     gateway: 192.168.16.1
     netmask: 255.255.255.0
         dns: 192.168.16.1
   ...

   dBUG> dnfl image.bin
   ...

   dBUG> dn empty.jffs
   Address:  0x4001FF80
   Downloading Image 'empty.jffs' from 192.168.16.100
   TFTP transfer completed
   Read 786432 bytes (1537 blocks)
   dBUG> fl w 0x740000 0x4001FF80 0xc0000
   ......
   Flash Write complete. 0xC0000 bytes written

   dBUG> dn etc.tar
   Address:  0x4001FF80
   Downloading Image 'etc.tar' from 192.168.16.100
   TFTP transfer completed
   Read 20480 bytes (41 blocks)
   dBUG> fl w 0x800000 0x4001FF80 0x5000
   Must erase complete sectors (0x00800000 to 0x0081FFFF)
   Continue (yes | no)? yes
   .
   Flash Write complete. 0x5000 bytes written

for the server, use ipsec-x509-linuxsdk.sh as a guide.