You can double escape the @@ like this. @@@ROWCOUNT.
You can see this technique used in the PetaPoco.cs file in the ExecuteInsert method.
public override object ExecuteInsert(
Database db,
System.Data.IDbCommand cmd,
string PrimaryKeyName)
{
db.ExecuteNonQueryHelper(cmd);
return db.ExecuteScalar<object>("SELECT @@@IDENTITY AS NewID;");
}