Right then.
Use PHP4
Create the database winestore with a hostname,user,userpass as usual from DH ControlPanel.
Edit the winstore database file from the ZIP called winstore.data and comment out the first three lines
drop database if exists winestore;
create database winestore;
use winestore;
to
#drop database if exists winestore;
#create database winestore;
#use winestore;
Resave winestore.data to say winestore.sql (I do not know if it would have worked with those lines left in probably would)
Log into the database winestore using PHPMyAdmin and select the database and use the import button and import winestore.sql from the PC to set up the tables and entries.
That completes the DB side.
Install the wda2-winestore folders and files from the PC to DreamHost under a folder name called wda2-winestore.
i.e. at /home/user/example.com/wda2-winestore
Now go to the includes folder and edit db.inc to show details of database name,hostname,user,userpass.
edit winestore.inc
set define("D_INSTALL_PATH",
to
define("D_INSTALL_PATH", "/home/username/example.com");
set define("D_WEB_PATH",
to
define("D_WEB_PATH", "/wda2-winestore/");
(default I think)
Scroll down a bit and set the location of the error log
define("ERROR_FILE", "/home/user/example.com/wda2-winestore/tmp/php_error_log");
and create that 'tmp' folder under wda2-winestore.
Now the tricky bit. I cheated here because I should have set up the local PEAR pathnames I suppose.
Copy the three files from your local PEAR/php folder called IT.php, IT_Error.php,ITX.php to your wda2-winstore includes folder. Open each file in turn and check that the require_once lines near the top of each file only contains a filename and not the path to the local PEAR folder where they once lived.
I think that should do it.
Run http://example.com/wda2-winstore/
That should give the index and clicking 'use the application' should...
It is a bit of a hodge podge but it gets the thing going. Something may break further along most likely.
Hopefully the authors will update it for PHP5
Even more hopefully somebody will rewrite the PEAR wiki to make it easier to use the environment settings!
--
Norm
Opinions are my own views, not DreamHosts'.
I am NOT a DreamHost employee OK!! 
You act on my advice at your own risk!