How to NANDroid a phone without ClockWorkMod?
First, some disambiguation is in order.

Amon_Ra is a developer who created one of the recovery consoles (named after himself.)  Just like ClockworkMod (which was created by a different developer named Koushik Dutta, a.k.a. Koush) Amon_Ra's Recovery performs various low-level tasks on Android devices.

Odin is a Windows application that can be used to flash firmware onto various Samsung Android handsets and tablets.

Heimdal is a cross-platform application (available for Windows, Linux and OS X) that uses the same protocol as Odin to interface with Samsung devices in "download" mode.

NANDroid is a script which runs in Android Recovery mode and dumps the image of the devices' partitions onto the external media such as SD Card.  It requires root and some other libraries to function properly.  For restoring, the recoveries use a different script which utilizes the fastboot binary to flash the image files created by NANDroid back onto their appropriate partitions.

With the above said, neither Odin or Heimdal can be used to take backups of devices; they are purely for flashing firmware onto them.  ClockworkMod or Amon_Ra Recoveries do include the NANDroid script.  However, due to the differences in partition layout, they need to be modified specifically for a given device they are ported to.  If you are knowledgeable enough, you can try to adopt the NANDroid script for use with Samsung Galaxy i551, and run it manually via ADB shell while the phone is in Recovery mode.  Again, you will need root privileges and other libraries compiled specifically for this device.