1) Uninstall any previous version of Diskeeper

2) Install Diskeeper 2010 Pro Premier 64-bit ( Vista and Win7 users, right click on the installer and run as adm )

3) When the installation is finished, close Diskeeper.

4) Go to Control Panel -> Administrative Tools -> Services and stop Diskeeper
or just press Start-> Run -> write: services.msc and press Enter
right click in Diskeeper and stop this service.

5) Copy the cracked file in install dir, by default:
C:\Program Files\Diskeeper Corporation\Diskeeper
And replace the existent file

6) Run the regfile "Register.reg" 

7) Go to Control Panel -> Administrative Tools -> Services and Restart again the service Diskeeper

8) Vista and Win7 users, right click on the shortcut of Diskeeper and select Properties. In the Properties window, go to the Compatibility tab. Check the option that says Run this program as an administrator and click on OK.

That's all, credits to Freddy for this crack.