I would like to have dock items for starting different web pages with different browsers. I have a number of programs that I use in my business that are cloud based. Some work better with Firefox, some with IE8, and some with Chrome. I can't figure out how to start them with anything other than my default browser.

Adding a URL to the dock will always open that web page on whatever is the current default browser.

If you want to open different web pages in different browsers, then you will have to add a shortcut to the dock that refers to the browser itself, and add the URL as an argument/parameter (right click the shortcut to the browser in the dock and select 'Dock Entry Properties'). For instance, for Firefox:

Filename: C:\Program Files (x86)\Mozilla Firefox\firefox.exe
Arguments: http://www.winstep.net
Start In: C:\Program Files (x86)\Mozilla Firefox\
etc...

This would start a new session of Firefox displaying the Winstep web site.