Sure,
for Social Science and History I only studied the official CLEP book (I did not know about InstantCert back then).
If you study the InstantCert and the Handbook, you should be fine. A lot of times, I just guessed and chose the most logic answer. It worked for me.

For the Information Systems I used InstantCert which was very helpful in regards to all the different terms. Also, try to do as many mock tests as possible and make sure, you have also have a quick look over the Management Information Systems InstantCert info (DSST test) and feel comfortable with terms like MIS and DSS.
(I looked over the InstantCert for the MIS test, chickened out and decided to go with the CLEP test first ;-))

Good luck,
kckusek

__________________
Passed in 2007 and DONE!!! :
CLEP:
30 credits
DANTES:
45 credits
ECE:
19 credits
NYU - German Proficiancy Test
16 credits
Traditional Course work:
12 credits