CVA with single-concept design will work, as long as the volumes that the respondent will specify are in the range 0-999. The software will not support values larger than 999.
You can use either OLS or HB-OLS estimation. Just make sure in the Analysis Manager to click the gear button (the settings button), then select the Scale link, then specify that Recode= "None".
With the dependent variable in its natural scale (0-999), meaning Recode="None", the sum of the raw part-worth utilities for the product concept will be the least-squares fit to the volume the respondent specified.
In other words, don't use zero-centered diffs rescaling to make the predictions of volume. Build your own simulator in Excel and compute the total predicted volume per respondent as simply the sum of the raw part-worths.
Or, if using our Advanced Simulation Module simulator, I think there is a way to tell it to report "total utility" rather than "shares of preference" and in that case our simulator will simply add the raw part-worths and report the total utility (which for you means total volume) for any product concept you specify in the simulator.