After reading many blog posts, TK articles, forum threads, and the like I pieced together from many sources how to build Visual Studio Toolkit forms that integrate with Dynamics GP security so you don't have to hard code a connection string or any environment specific settings in your application or .config file.
You'll need to get the GP Connection Library (GPConn.dll) from GP Support. You have to license the GP Connection object and obtain the keys. This will enable you to get around the VS Toolkit only exposing the unencrypted password. Once you have that you can simply use the code snippet below in your project to dynamically connect to the Dynamics GP database using the GP user credentials.
Dim resp As Integer
' Create the connection object
GPConnObj = New Microsoft.Dexterity.GPConnection()
resp = GPConnObj.Init("key1", "'key2")
CompanyDB.ConnectionString = "DATABASE= " & Dynamics.Globals.IntercompanyId.Value
GPConnObj.Connect(CompanyDB, Dynamics.Globals.SqlDataSourceName.Value, Dynamics.Globals.UserId.Value,
This is mostly straight from the documentation that accompanies the GP Connection Library from GP Support. From that, it was easy and convenient to build the connection string using Dynamics.Globals.IntercompanyID for the database and SqlDataSourceName for the SQL Server Instance in the connection string. The UserID and SQL Password need no explanation. Now, you can compile your .dll and deploy it to any GP installation without having to worry about any environment specific settings.
I'm sure there are more elegant ways of doing this and this may been clearly documented elsewhere but I didn't find it teed up for me this way. That would have saved me a little time. I hope this helps you!