I found quite a few Miller Lite contests, but most did not have the keyword in the details. What I have done before is trying different words to get a hit on a keyword (try the words on the particular contests).
http://www.promorules.com/ml2336/
(keyword mmddyyyy) to short code “49375 (?? keyword)
This sweepstakes is open only to residents of CT, NH, MA, ME, RI and VT
The Miller Lite Boston Celtics Flyaway Sweepstakes (the "Sweepstakes") begins at or about 12:00:01 AM (ET) on 12/01/10 and ends 11:59:59 PM (ET) on 03/15/11 (the “Promotion Period”).
PRIZES AND APPROXIMATE RETAIL VALUES (ARV): Eleven (11) Grand Prize: prize includes a 3-day/2-night trip for winner and one (1) adult guest to Miami, FL on or about 04/09/2011 – 04/11/2011. Prize includes round-trip coach air transportation from the commercial airport nearest the winner's home to Miami, FL, 2-nights standard hotel accommodations (one room/double occupancy), two (2) tickets to attend the Boston Celtics away game on or about 04/10/2011, transportation to and from hotel/airport in Miami, FL and $100.00 spending money, awarded in the form of a check. ARV $2,000.00
http://www.promorules.com/ml2441/
Text keyword to 42653
The Miller Lite March Hoops Sweepstakes (“Sweepstakes”) is open only to legal residents of FL, GA, IL, IN, KY, MA, MD, MI, NC, NY, OH, PA, RI, SC, TN or VA who are 21
The Sweepstakes begins at 12:00:00 AM ET on 03/13/11 and ends 11:59:59 PM ET on 04/09/11 (“Sweepstakes Period”
APPROXIMATE RETAIL VALUE (“ARV”): Three (3) Grand Prize Per Promotion Period (21 Total Grand Prizes): prize includes one (1) Miller Lite basketball and one (1) Miller Lite basketball jersey. ARV: $100.00. Limit one (1) prize per household/address. Total ARV of all prize(s): $2,100.00.