The TCL 55P605 does not ship with the enhanced remote; therefore the enhanced functions for pairing are hidden. I paired the enhanced voice remote from a Roku 3 with my TCL 55P605. You have to enable full UI support for the enhanced remote in order to pair it by one of the following methods (from AVSForum.com posts):
1) SYSTEM RESTART of the TCL 55P605 TV from SETTINGS -- SYSTEM - POWER - SYSTEM RESTART menu and then using the pairing button on the enhanced Roku remote.
2) Access one of the Roku secret menus with the existing TCL infrared remote:
Home x 5, FF, Play, RW, Play, FF
-> "RF Remote Menu"
-> "Enable full UI support for remote"
I used method 2) and then paired my Roku 3 remote with the 55P605.