You're looking for ColumnAttribute.AutoSync. If you're using the designer, check each column for an Auto-Sync property and set it to Never.
Edit:
Ok, that didn't work for you. Brace yourself for some mapping hackery!
When I Insert with some autogenerated primary key column, I get this SQL:
INSERT INTO [dbo].[TableName]( fieldlist )
VALUES (@p0, @p1, @p2, @p3, @p4)
SELECT CONVERT(Int,SCOPE_IDENTITY()) AS [value]
As I understand your request, you don't want that SELECT
Attempt 1: I went to the primary key field and set auto-generated to false. This caused a Sql Exception "Cannot insert explicit value for identity column in table 'TableName' when IDENTITY_INSERT is set to OFF." In other words, linq specified a value for that column.
Attempt 2: I deleted the autogenerated columns from the designer. This caused Linq to give me an Invalid Operation Exception: "Can't perform Create, Update or Delete operations on 'Table(TableName)' because it has no primary key."
Attempt 3: I deleted the autogenerated columns from the designer, then I marked another column as primary key. Even though this column is not a primary key in the database, LINQ's DataContext will use it to track row identity. It must be unique for observed records of a given DataContext.
This third attempt generated the following SQL (which is what you ask for)
INSERT INTO [dbo].[TableName]( fieldlist )
VALUES (@p0, @p1, @p2, @p3, @p4)