CLR Triggers, Linq, And Transactions

I'm trying convert my working CLR Trigger to a Linq-based implementation, but I don't seem to be able to get Linq to cooperate with the Trigger's context transaction (a local SubordinateTransaction with IsolationLevel="ReadCommitted").

For brevity's sake I've boiled down my scenario to a bare minimum: A SQL table [Test] with three columns (int Manual, int Automatic, IDENTITY int ID) needs any external updates on its [Manual] column to be applied to its [Automatic] column (with an additional sign change) through a Trigger.

A fairly direct translation of my non-Linq CLR Trigger to Linq yields the following code (the [Trigger_TestLinQs] SQL table has been modified to point to the Trigger's "INSERTED" table, [TestLinQs] points to the actual SQL table):




Code Snippet[SqlTrigger(Name = "LinQTrigger", Target = "dbo.TestLinQ", Event = "FOR INSERT, UPDATE")]
public static void LinQTrigger()
{
SqlTriggerContext triggerContext = SqlContext.TriggerContext;
if (triggerContext.TriggerAction == TriggerAction.Insert || triggerContext.TriggerAction == TriggerAction.Update) {
//using (TransactionScope scope = new TransactionScope(Transaction.Current)) { /* err 6549 */ using (SqlConnection connection = new SqlConnection("context connection=true")) {
connection.Open();
using (MyDataContext context = new MyDataContext(connection)) {
List<int[]> updates = new List<int[]>();

foreach (Trigger_TestLinQ test in (from t in context.Trigger_TestLinQs select t)) { /* err 6522 */
if (test.Manual != null && triggerContext.IsUpdatedColumn(0))
updates.Add(new int[] { test.ID, -test.Manual.Value });
}

foreach (int[] update in updates) {
dbo.TestLinQ test = (from t in context.TestLinQs where t.ID == update[0] select t).Single<dbo.TestLinQ>();
test.Automatic = update[1];
}

context.SubmitChanges();
}
}
// scope.Complete(); //}
}
}
Running this on SQL Server 2005 / .NET 3.5 beta2 produces an Error 6522 "Cannot enlist in the transaction because a local transaction is in progress on the connection." in the line executing the Linq query because the Linq DataContext apparently insists on opening a transaction.
The recommended pattern for DataContext query operations - running them inside a TransactionScope as indicated by the commented-out sections - unfortunately leads to a different Error 6549 in the TransactionScope constructor complaining about a missing MSDTC. And there shouldn't be a need for a distributed transaction here, should there?
Using different TransactionScope constructors (TransactionScopeOptions.Required, TransactionOptions(){IsolationLevel=ReadCommitted}) did not make any difference, either.

What am I doing wrong here? Is there any way for the Linq DataContext to attach to the CLR Trigger's ambient transaction?