It depends on the exact version of ClearCase.
CCRC (ClearCase Remote Client, 7.1.X up to 8.0.1) for example, has quite a number of limitation when integrated ClearQuest (swg21398642).
If this is CCRC, see "CCRC supports the UCM integration with ClearQuest"
If it is not CCRC, then check "Establishing the Rational ClearQuest Web interface", which does mention:
If the Rational® ClearQuest® client is installed on a developer system, it is used by default.
If the Rational ClearQuest client is not installed on a developer system, the Rational ClearQuest Web Interface is the default interface.
To enable a client to use the Rational ClearQuest Web Interface, set the following configuration parameters in the configuration file or the environment variables from the command-line prompt: