Can I use The Roku box to get MyTV IL, if yes, how?
I recommend contacting the live support team available through the official website. I have checked the supported features as well as the channels, but I couldn't find anything related to the MyTV-IL website/service.
Use the following link to access the support page: https://support.roku.com/hc/en-us then click the blue button on the right. They should offer you all the necessary information regarding this procedure.