ActiveDocument = oleWord.GetType().InvokeMember("ActiveDocument", BindingFlags.GetProperty, null, oleWord, null);

class Word
    {
        private object oleWord = null;
        private object Documents, WorkBook, ActiveDocument, Tables, Table, Cell, Range;

        public Word()
        {
            oleWord = Activator.CreateInstance(Type.GetTypeFromProgID("Word.Application"));
        }

        public void Open(string TemplateFileName)
        {
            Documents = oleWord.GetType().InvokeMember("Documents", BindingFlags.GetProperty, null, oleWord, null);
            WorkBook = Documents.GetType().InvokeMember("Open", BindingFlags.InvokeMethod, null, Documents, new object[] { TemplateFileName, true });
        }

        public void TableSelect(int TableNum)
        {
            ActiveDocument = oleWord.GetType().InvokeMember("ActiveDocument", BindingFlags.GetProperty, null, oleWord, null);
        }
...

    [Microsoft.SqlServer.Server.SqlProcedure]
    public static void proc1(SqlString filename_tempalte, SqlString filename_invoice, SqlString data, out SqlInt32 result, out SqlString msg)
    {
        try
        {
            Word W = new Word();
            W.Open(filename_tempalte.ToString());

            W.TableSelect(1);//Выбираем нужную таблицу

            result = 0;
        }
        catch (Exception Err)
        {
            result = -1;
            msg = "Ошибка: " + Err.Message;
        }
    }

IF  EXISTS (SELECT * FROM sys.assemblies asms WHERE asms.name = N'SQL_CRL') DROP ASSEMBLY SQL_CRL
GO
CREATE ASSEMBLY SQL_CRL FROM 'c:\windows\system32\SQL_CRL.dll' WITH PERMISSION_SET = UNSAFE
GO

CREATE PROCEDURE [dbo].[proc1](@filename_tempalte [nvarchar](4000), @filename_invoice [nvarchar](4000),
@data [nvarchar](4000), @result int out, @msg [nvarchar](4000) out)
AS 
EXTERNAL NAME SQL_CRL.[SQLU].[proc1]
GO