How to score V45+?

A 45+ score in Verbal is very, very rare. Unlike in Quant, only 1% of test takers score 45 or higher in Verbal. (In Quant, the corresponding figure is 46%.)

Additionally, there's something interesting and a bit mysterious going on with the scoring algorithm with regards to Verbal versus Quant. In my analysis of GMAT enhanced score reports, I've found that people who score very well in Quant often miss a decent number of questions in the Quant section. However, people who score very well in Verbal typically miss very, very few questions, sometimes none at all. I don't know whether that means you have to get more questions right on Verbal to score very well; after all, the algorithm definitely doesn't directly factor in how many questions you get right, so it should be possible to score well with more wrong answers. But it's a trend: on Verbal, people who score very well tend to be the ones who miss almost no questions, while on Quant, many high scorers still miss a lot of questions.

To answer your question more directly: what do you mean by official material? Don't forget about the Guide to Verbal Review supplement for the Official Guide, which has a lot of additional CR questions. There's also the Extra Questions Pack from the GMAC, which you can purchase once you have access to GMATPrep.