Alright I could quote almost every post thus far. The multisite tool if I am not mistaken will help to manage multiple sites that are already installed and running. It appears from the questions asked that the issue is how to use one hostname and one database to provide more than one unique store.
The only part that seems to be missing is the step(s) to use the one database. Stevesh already provided directions to use multiple folder locations. To use the same database for each store but have them operate indepedently, use a different table prefix during installation/setup for each store. Recommendation is that the last character of the prefix be an underscore such as 'zen_'
Once the multiple stores are setup, then maybe the multi-site manager will be of more value/use.
ZC Installation/Maintenance Support <- Site
Contribution for contributions welcome...