...It uses ClamWin's virus database, so ClamWin is required.
If you have ClamSentielPortable next to ClamWinPortable, then ClamSentinel will detect ClamWin's database. For example, if ClamSentinelPortable is installed in folder A (/A/ClamSentinelPortable/App,etc) and ClamWinPortable is also in folder A (/A/ClamWinPortable/App,etc), then it will detect it.