The forward, 22, signed for the Eagles in January having predominantly made his name in non-league football and went on to make four substitute appearances in the Championship towards the back end of last season.
Appiah stepped off the bench a further three times at the start of this campaign before making his first start for Palace in their 4-1 Capital One Cup defeat to Preston at the end of last month.
Shots boss Dean Holdsworth told the club's official website "Kwesi comes highly recommended and is a player that I am looking forward to working with.
"Whilst we have other strikers out on loan acquiring valuable game time, the arrival of Kwesi gives us another option and a month to look at him."
