Alas, Ceasars Indiana, the poker room is still many ways the stepchild of the Casino, and last I heard they don't give a poker rate.
The only exception is during the WSOP Circuit Event, when they give out a special code for you to book your rooms at the special rate. If you are coming for the WSOPCE, be sure to use the code given in the press release for the WSOPCE announcements on the
http://www.worldseriesofpoker.com website. There is also a thread in the Tourney forum (under the Tunica Thread) that gives that code, that's the same at all Harrah's properties when booking rooms for the WSOPCE.
BTW, if you stay at Ceasars Indiana, be sure to bring earplugs with you, as the walls in the rooms are paper thin, and you won't be able to sleep due to noise unless you bring those earplugs.
However, the beds are wonderful there, you'll sink right into them, they are that comfortable.
Edit: Try this code here:
Corrected code: CO9W0RL (second 'oh' is a zero - think of it like this: Co9W0RL)