What version you have ?
Do you have the Dext tools ?
The helps it self can assist you how to do that
Couple things to know before we get started here:
1. Modifier creates modified windows or modified alternate windows
2. You cannot use Dexterity to create an alternate version of a third party resource. Even if you were to do a Developer Update with Dynamics Utilities to merge the Dynamics and the Project Accounting dictionaries to create your customization, you would still face the issue of extracting your resources from those of the Project Accounting dictionary.
As it stands, you have 3 options:
1. Merge the Dynamics dictionary with the project dictionary, then transfer the window with all the associated tables to a new development dictionary (your development dictionary) to implement all the changes to the UI. This will also transfer all fields and data types needed to support the window and table fields. The only downside to this is you have to build all the code that would otherwise exist on the standard project window yourself, which means, you would have to be very familiar with the functions of that window.
2. Create a companion window and table to the window in Project that you want change. This companion window will allow you to add any fields, etc, that you want to implement, then use triggers to drive the CRUD operations based on the behaviors on the main window.
3. Use Modifier to implement the changes to the UI, then use Visual Studio Tools to drive the code.
Take a look at the sample code that David Musgrave and I built and presented at Convergence 2010 Atlanta:
Microsoft Dynamics Convergence 2010 - Wrap Up and Materials
You will also want to look at the Pushing the Limits with Dexterity material available on the Developing for Dynamics GP website.
Cross Dictionary Dexterity Development
I should mention that suggestion 1 is actually in breach of the license agreement.
Have a look at these posts on the topic.
Understanding Cross Dictionary Dexterity Developmenthttp://blogs.msdn.com/b/developingfordynamicsgp/archive/2009/09/18/understanding-cross-dictionary-dexterity-development.aspx
Can I customise a 3rd party form with Dexterity?http://blogs.msdn.com/b/developingfordynamicsgp/archive/2008/11/10/can-i-customise-a-3rd-party-form-with-dexterity.aspx
Cross Dictionary Dexterity Developmenthttp://blogs.msdn.com/b/developingfordynamicsgp/archive/2008/07/24/cross-dictionary-dexterity-development.aspx
David Musgrave [MSFT]Escalation Engineer - Microsoft Dynamics GPMicrosoft Dynamics Support - Asia Pacific
Microsoft Dynamics (formerly Microsoft Business Solutions)http://www.microsoft.com/Dynamics
mailto:David dot Musgrave at microsoft dot comhttp://blogs.msdn.com/DevelopingForDynamicsGP
Any views contained within are my personal views and not necessarily Microsoft policy.This posting is provided "AS IS" with no warranties, and confers no rights.