I think this depends on exactly what you're trying to measure. Do you mean in AC analyses, such as filter responses, or are you looking for the ESR of a capacitor?
In the first case, go to LT Spice, set up an R-C filter or some such thing, click Run, and you'll get a dialog box; go into the AC analysis section, fill out your frequencies etc. and it will run, showing you (in dB) the loss WRT reducing frequency in a nice curve. You could enter the formula for converting dB to V if you like; play around with it.
If it's the 2nd case (finding ESR), that is a lot more difficult, and not as big an issue unless you're doing something involving really high freq's....you can simulate it with a 1 to 10 ohm resistor in series with the cap to estimate increasing ESR with age...but each cap's will be different, and actually requires measurement with a frequency generator.