LINQ-to-SQL: Stored Procedure that returns a single scalar value?

private ISingleResult<sp_xal_seqnoResult> NextRowNumber([Parameter(DbType="Int")] System.Nullable<int> increment, [Parameter(DbType="Char(3)")] string dataset)

<Function Name="dbo.foo" Method="foo">
    <Parameter Name="inc" Type="System.Int32" DbType="Int" />
    <Parameter Name="dataset" Type="System.String" DbType="VarChar(20)" />
    <Return Type="System.Int32" />
</Function>

[Function(Name="dbo.foo")]
public int foo([Parameter(DbType="Int")] System.Nullable<int> inc, [Parameter(DbType="VarChar(20)")] string dataset)
{
    IExecuteResult result = this.ExecuteMethodCall(this, ((MethodInfo)(MethodInfo.GetCurrentMethod())), inc, dataset);
    return ((int)(result.ReturnValue));
}

<Function Name="dbo.foo" Method="FooPrivate" AccessModifier="Private">
    <Parameter Name="inc" Type="System.Int32" DbType="Int" />
    <Parameter Name="dataset" Type="System.String" DbType="VarChar(20)" />
    <ElementType Name="fooResult" AccessModifier="Internal">
      <Column Name="value" Type="System.Int32" DbType="Int NOT NULL" CanBeNull="false" />
    </ElementType>
</Function>

[Function(Name="dbo.foo")]
private ISingleResult<fooResult> FooPrivate(
    [Parameter(DbType="Int")] System.Nullable<int> inc,
    [Parameter(DbType="VarChar(20)")] string dataset)
{
    IExecuteResult result = this.ExecuteMethodCall(this, ((MethodInfo)(MethodInfo.GetCurrentMethod())), inc, dataset);
    return ((ISingleResult<fooResult>)(result.ReturnValue));
}

namespace MyNamespace {
    partial class MyDataContext
    {
        public int Foo(int? inc, string dataSet)
        {
            return FooPrivate(inc, dataSet).Single().value;
        }
    }
}