Not using DDE, you need to use automation:
HOWTO: Automating Visual Studio .NET from outside the IDE.
http://www.mztools.com/resources_vsnet_addins.htm
Once you have a DTE instance the easiest way is to call
DTE.ExecuteCommand("Edit.GoTo", linenumber)

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Best regards,
Carlos J. Quintero
MZ-Tools: Productivity add-ins for Visual Studio
You can code, design and document much faster:
http://www.mztools.com
> We are using DDE to open a file in VisStudio2005, but is there a way
> to have it also go to a specific line in that file?