As far as I know you can't. PVElite is made to perform calculations according to ASME VIII (and other codes), not to exclude items from the calculation.
Although this is sort of done for standard flanges where the P/T rating can be used.

B16.9 fittings are strange things as B16.9 doesn't state the thickness of the fittings. It only states that it may be considered as a straight pipe with the same schedule as for which the fitting is tested. This however doesn't say anything about the exact shape and thickness. Therefor calculating the MAWP based on geometrical parameters is difficult.

Best thing to do is to model a cone, and add a note in your report that the calculation is not required with reference to B16.9.