Sure! Select a list from My Lists and select List Profile from the menu then select “Merge Into Timeline”. You will see an indicator next to your timeline icon, and an indicator on each tweet from the list.
Please note that if you add multiple lists to your timeline, there will be no further indication as to which list the tweet came from.
To remove a list, select “Remove from Timeline” from the List Profile.
SHORTCUT: Long press on the bird icon in the Navigation Bar. You will be given an option to Edit Timeline Lists. Use checkboxes to add/remove SmartLists from your timeline.