No, you can't specify in UltraEdit how the default browser opens the page. This is a browser setting, which UltraEdit can't know. If you want a special file open handling, you have to specify it in your browser.
Instead of using the "Show File in Browser" feature, you can also set up an user tool, where you can start the browser you want with the current file and the command-line switches you need. You then can reconfig the hotkey for "Show File in Browser" to your user tool.
Command-line switches for IE see http://support.microsoft.com/kb/178058/en-us
Command-line switches for Opera see http://www.opera.com/support/mastering/ ... l#commands
I use Opera, but here is an example for Internet Explorer for the tool configuration which always opens the current file in a new instance of IE.
Command Line: "C:\Program Files\Internet Explorer\iexplore.exe" -new "%f"
Working Directory: %p
Menu Item Name: Show with IE
Save Active File
You can also extract the IE standard icon from iexplore.exe for example with IrfanView and add this icon to this tool.