If only the guards in CI Defense didn't have shields. Anyways, are sure the walkthroughs don't help because the walkthrough at Perfectlydark.com helped me heaps on that mission on Perfect Agent. If you haven't seen it, then I suggest you do because the walkthrough is in a video format, not text. Here is the direct link to the PD Video walkthrough page at Perfectlydark.com

I can't really help you with Attack Ship since i'm not the one that beat it so ask someone else or ask Chindar. He should be a bigger help.

http://www.perfectlydark.com/moviewalks.shtml
(The 3rd one is the one)