IMC Confuser? I thought these were like the proverbial rocking horse stool?
Unless you have a fetish for the Confuser series (as many do) I suggest that 'Book 5' is all that is needed. I used the standard Air Pilot Publishing Air Pilots Manual 5 for the IMCr as well as PPL training and didn't have any issues with the exam(s) or understanding the theory prior to practical application of the concepts.
The IMC exam is very much like the PPL Nav exam: a load of multiple choice questions followed by a planning/plogging exercise. The only word of caution is to work your timings out and rely on them (a few 30 seconds here and there will make a 100% pass into 92% pass!).
Good luck guys!
GW