Richard,

The way I've found to do it (with suggestions from support) is:

1. Call GetUserIdentities() and verify the user ID exists.
2. Call GetUserProfile() to get the user's profile. The password exists as a property of the profile.
3. Call UpdateUserProfile() with the new profile proerties.

I haven't tested this from end-to-end due to working with encrypted passwords, but the data and methods are there.

Thanks,
Jonathan