If there is any Adobe Camera RAW Update available for CS5 that will add those two camera models, then install. Else you have no chance and would have to uses a different RAW converter tool.
evjems, As per the below article, Canon EOS 1100D needs minimum Adobe Camera Raw(ACR) version 6.4 and Canon EOS 650D needs minimum ACR version 7.1
So, you should be able to open raw files of 1100D, if you upgrade your PS ( Help > Updates), but not of 650D as it needs PS CS6 and above.
Let me know in case you still have any doubts.
Hope that Helps!