^ yes, through select. In my case, when I changed my plan from Gold to Dual Def 499, we added Disney Jr., Nick Jr., and History Channel. All SD channels.
However, Sky recently added History HD, so we called to cancel History SD. But according to Sky, no need na daw since History SD has become a regular channel line-up for Dual Def.
Which channels from Gold do you like added? There are several plans in Dual Def, you may want to check their respective channel line-ups.