Based on this Reddit post it sounds like it should be relatively simple to set the announcer from any announcer you own in arcade and custom campaigns. https://www.reddit.com/r/starcraft/comments/5899l5/do_the_new_paid_announcer_work_in_arcade_games/
I poked around a bit but couldn't figure out where to go to change the CGame_EnableRewardVoicePacks value, and throwing that term into Google only brought up the page above. If anyone could point me in the right direction that would be great.
Likewise, is there a way to use the SC1 announcers when playing custom single player maps in SC1? Does it work by default or do you have to mess with it?
Any help would be appreciated.