When hcron executes an event, it does so with a minimal environment. This means each event must set up the environment as appropriate for itself. The brute force way way is to run a shell as a login shell, which will provide an environment almost equivalent to an interactive session (as shown below).
command=csh -l -c "<commands here>"
For enterprises in which a large number of events may be launched at once, even across multiple hosts, loading a full login environment for each event is highly discouraged as it can put a significant and unnecessary load on the home file servers. Ideally, augment the environment only as needed for the event command to run.