Shipsey recommends Wellman's book: http://www.ethosdebate.com/2011/01/reco ... amination/
When I see good debaters take their CXes to the next level, typically they have stopped asking questions about what the other team just said and instead find assumptions and agreement for what they intend to argue in the next speech or already did argue. Getting people to agree with the OVERALL point, though of course they don't think your particular case/neg actually matches it, can be done by searching for the ideal in CX. A kind of "let's get on the same page about how things SHOULD be" attitude that sets up your speeches to run through the test you just agreed on.
As for actual phrasing:
- Isn't it true that ______ ?
- Does ______ happen?
- But it's a fact that ________ ?
- Surely _______ ?
- We've all been in a situation where __________ ?
- What would you choose if ________ or ________ ?
- In your 1NC you argued X, isn't that so?
- And the proof you offered was N?
- No, I don't need you to re-explain it, just confirming your argument.
- But in our 1AC we quoted Z person to say [Y warrants]. You'd agree that N doesn't really address Y?
- (now walk them through your logic)
- Now given [situation], wouldn't Y seem to hold true?
- I mean obviously we wouldn't want not-Y, right?
- So at least SOME of the time, the non-X part of the time, Y is correct?