changing host password via perl SDK?

Can anybody provide a quick pointer on how to change the root password using the perl SDK?

It appears that I need to create a hostConfigSpec (with userAccount property) and call applyHostConfig_Task to achieve that. But I am having a hard time figuring out the structure of hostconfigSpec piece...

In addition, if I want to only get the properties needed to speed up the query, what properties should I filter on?

$hosts = Vim::find_entity_views(view_type => 'HostSystem', properties => ['name','config'], filter => { name => qr/$hostName/});

Thanks!