Thanks to fredvries, here's how to add support for 52%:
Copy and paste this into C:\Program Files\CCleaner\winapp.ini (or winapp2.ini if you have the extra cleaning provided by Twisted Metal)
[Alcohol 52%]
LangSecRef=3024
Default=True
Detect=HKCU\Software\Alcohol Soft\Alcohol 52%
RegKey1=HKCU\Software\Alcohol Soft\Alcohol 52%\MountedMRU
Tested and works a treat.
Many thanks!