Row-Level Update Lock using System.Transactions - ado.net

Question

I have a MSSQL procedure with the following code in it:
SELECT Id, Role, JurisdictionType, JurisdictionKey
FROM
dbo.SecurityAssignment WITH(UPDLOCK, ROWLOCK)
WHERE Id = #UserIdentity
I'm trying to move that same behavior into a component that uses OleDb connections, commands, and transactions to achieve the same result. (It's a security component that uses the SecurityAssignment table shown above. I want it to work whether that table is in MSSQL, Oracle, or Db2)
Given the above SQL, if I run a test using the following code
Thread backgroundThread = new Thread(
delegate()
{
using (var transactionScope = new TrasnsactionScope())
{
Subject.GetAssignmentsHavingUser(userIdentity);
Thread.Sleep(5000);
backgroundWork();
transactionScope.Complete();
}
});
backgroundThread.Start();
Thread.Sleep(3000);
var foregroundResults = Subject.GetAssignmentsHavingUser(userIdentity);
Where
Subject.GetAssignmentsHavingUser
runs the sql above and returns a collection of results and backgroundWork is an Action that updates rows in the table, like this:
delegate
{
Subject.UpdateAssignment(newAssignment(user1, role1));
}
Then the foregroundResults returned by the test should reflect the changes made in the backgroundWork action.
That is, I retrieve a list of SecurityAssignment table rows that have UPDLOCK, ROWLOCK applied by the SQL, and subsequent queries against those rows don't return until that update lock is released - thus the foregroundResult in the test includes the updates made in the backgroundThread.
This all works fine.
Now, I want to do the same with database-agnostic SQL, using OleDb transactions and isolation levels to achieve the same result. And I can't for the life of me, figure out how to do it. Is it even possible, or does this row-level locking only apply at the db level?