No, with the recent changes on the Facebook policy, it is no longer possible to request users to 'Like' the Facebook page in order to be able to vote in a promotion or contest. This requirement can neither be applied for users who vote in a contest.
As alternative, Easypromos provides 'My Networks' module, which allows to suggest the user to optionally 'Like' a Facebook page and even follow a Twitter account. 'My Networks' module allows to totally customize the screen displayed to the user right before submitting the registry form to encourage the user to become a fan. Administrators will be able to add as many Facebook pages and Twitter accounts they wish.