1. Install the Hierarchical Select module in sites/all/modules
  2. Navigate to /admin/build/modules and enable the module and appropriate helper modules.
  3. Navigate to /admin/admin/config/content/hierarchical_select and setup your global settings
  4. Create a term reference field and select the "Hierarchical Select" widget type.
  5. Set the relevant settings for that field.

To consider:
If your vocabulary was set to "tags" under the "Settings" section you will not get any options to configure Hierarchical Select on that vocabulary.
If you still want a "tagging" system you can still select "Allow creation of new terms" and Hierarchical Select will add a "create new item" to the drop down selection.

If you are having issues with your javascript not working see http://drupal.org/node/734178

Comments

Enzman’s picture

Enzman commented

I'm wanting to make a simple dropdown box that links to new pages or views - users select a different sort of a view form a simple UI that appears in a node. The user will be able to select longest, shortest, lowest price, highest price etc.

Have followed the instructions until:

4. Create a term reference field and select the "Hierarchical Select" widget type.

First question is "how?". (I'm not exactly sure what a reference field is). Do I do that through Views, Content Types or Taxonomy? That single line assumes I know, and has so far cost me a few hours of searching.

Overall, the documentation for this module is excellent, however I am lost on point 4.
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Still unsure. Have created some terms and am now wondering where to select the widget???
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Gave up. Too hard. Will implement the Custom Search module instead. Shame. I preferred the simpler vision that I had, thankfully had not shared it with the client.