Unfortunately, Roku is no longer supported.
To support Roku in Marmalade SDK, it requires Roku's proprietary SDK added in Marmalade. Previously, it's under protection of an agreement between Roku and Marmalade Technology. That agreement had been expired earlier, and Roku had been removed since SDK 8.7.
That is to say, even current latest Marmalade SDK had stopped supporting Roku. Given this situation, the upcoming SDKs won't have Roku support either.