Start vote and finish vote period with cron

[Teck]

Hi:
We are making some contest mensually, and I want know if is possible setup a cronjob for start automatically the vote period and for finish the vote period.

Maybe making 2 php files for alter the value of " pp_categories -> idofcategory -> takevotes = 1"?

Then, I can make the same php file for close the contest (I don't know if its takevotes = 0 or takevotes = 2, but I will look one when I finish the first).

At same time, I plan to change upload permisions with that php if I can.

I'm not a php/mysql programmer, so if somebody can help me I will apreciate

Tnx in advantage.