TechTool Pro 8  provides the ability to create an eDrive on the active system volume. 

To create an eDrive:

Always remember to backup important data prior to performing major operations such as eDrive creation or removal, optimizations, and volume rebuilds. The eDrive creation routine will create a 15 GB eDrive bootable volume. Confirm that the selected eDrive Destination Volume will have at least ten to fifteen percent free space remaining after the creation of the eDrive volume.

Launch the installed version of TechTool Pro 8 and click on the Tools category.

Click on the eDrive tool.

Select the active system volume as the eDrive Destination Volume and choose a bootable system volume for the Mac OS X Source Volume. By default, the current active system volume is already selected as the Mac OS X Source Volume.

NOTE: If there is an external or secondary internal hard drive, you have the option of selecting that as the eDrive Destination Volume.

Click on the Create eDrive button. The time to create a bootable eDrive volume will vary from machine to machine. Let the eDrive creation process continue until completion.

To boot the eDrive volume, click on the eDrive Restart button in TechTool Pro's eDrive configuration window or by restarting the computer, holding down the "option" key on the keyboard and selecting the eDrive icon.