Regular gels won't work for hair that length, not even sure that the super strong stuff (hair glues and cements) will either. Usually in movies when you see people with really long hair sticking straight up, or even in fashion/hair shows, it's usually supported with wire or pins of some kind that are hidden by the rest of the hair.
The following discussion board probably has the best advice for what you are looking for -
To make your hair a foot of hair stand straight up all day, you need to use a shampoo without a conditioner. Towel-dry your hair and apply the gel, Lemon Sage, which is the best for straightening hair form the root to the tips. Dry your hair using the dryer on the lowest setting to dry the roots. Finally, apply another amount of gel to your hair, spray and style as desired.