New update for the plugin is now available at the top of this thread.
A new render pass selection bar has been added to the right hand side of the Octane Render View Port. When denoising has been enabled in the Imager settings then you will see two entries (Main, DeMain). Main is the beauty pass and DeMain is the denoised beauty pass. Note that if the denoiser is set to denoise at the end of render then the DeMain pass will not show the denoised image until after the Main pass has completed.
Also note that if you want to generate an animation using the denoised image then you need to select the DeMain pass before you start rendering the animation.