First, install the required tools as described on this page.
Building the Phonegap Symbian package
Note that Nokia's WRT Plugin for Aptana studio will handle much of the following setup for you.
In your favourite text editor create a file called info.plist. This will be an xml file definining the properties of your app. Here is an example; the individual elements are self-explanatory.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Nokia//DTD PLIST 1.0//EN" "http://www.nokia.com/DTDs/plist-1.0.dtd">
<plist version="1.0">
<dict>
<key>DisplayName</key>
<string>Pigeon</string>
<key>Identifier</key>
<string>com.pigeon.basic.widget</string>
<key>Version</key>
<string>0.0.1</string>
<key>AllowNetworkAccess</key>
<true/>
<key>MainHTML</key>
<string>index.html</string>
<key>MiniViewEnabled</key>
<false/>
</dict>
</plist>
Next create an html file called index.html, in the same folder as above. Copy phonegap.js into this folder as well, and include it in your html page:
<script type="text/javascript" src="script/phonegap.js"></script>
Now phonegap's api will be available to your web-app, to make calls from javascript such as navigator.geolocation.getCurrentPosition(suc,fail, opt) or navigator.notification.vibrate(). Refer to the pigeon.js in the Pigeon sample app, or the api docs, for example code.
Once you have some ui objects and some device functionality you'd like to test, you need to package your widget.
Packaging your PhoneGap Symbian WRT Application
Simply create a zip compressed file containing info.plist, index.html, and all of your scripts, images, stylesheets, and other assets. Then rename the file to a .wgz extension, so that it is recognizable by Symbian OS as a WRT Widget Package.
Running on the Emulator
So after installing the S60 5th Edition SDK and its prerequisites, if you are looking to test with the Satio skin, then you should have download and run the Satio installer, which changes the S60 emulator to the Satio skin.
Now to run the simulator, go to Start -> Programs -> S60 Developer Tools -> 5th Edition SDK -> v1.0 -> Emulator.
In the emulator window, go to File -> Open, and select the .wgz compressed file which contains your web app. Follow the onscreen prompts to install the application. Now run it by Selecting the Menu -> Applications -> Pigeon (or whatever you named your application). Voila.