Help with initial multisite install in subdirectories

I am using JustHost and am trying to do the initial install(they offer 3.0), which I then want to upgrade to 3.0.1. I want to set up multiple sites in subdirectories. I am reading the latest WordPress for Dummies book and see the following instructions are necessary to enable a network:

mod_rewrite must be enabled in Apache file httpd.conf. Also, the <VirtualHost> section of the Apache file httpd.conf must be modified as follows:
AllowOverride None
should be changed to:
AllowOverride FileInfo Options
as well as adding:
ServerAlias *.hungryhappyhealthy.com
This last line is supposed to define the host name for my network site.

I do not have access to the Apache file and here is the non-helpful instructions sent to me from tech support:

“let me to explain:
you don’t have access to modify Apache settings
You can set needful changes in your .htaccess file.
The rewrite_mod is enable on the server
All settings that you want to add to Apache you can add to your .htaccess file
Also you can modify permalinks in the admin area of the WP software
You can create .htaccess file via Cpanel >> File manager in any folder of your account
You’ll be able to edit your rules there via Cpanel >> File manager >> Editor”

There is a 1-step install for WordPress 3.0 on the site, but I don’t believe it allows for the multisite option on setup or is that something that you do later? Also, do I need to set up multiple MySQL databases for each subdirectory? I see conflicting information on that topic as well.

As you can tell, I am totally lost. Pretty sad when the Dummies book isn’t Dummy enough for me. Anyone out there that can give me some helpful step-by-step to make this happen? Thank you in advance!