As long as you have the right value (250K, 500K, etc.) that you're looking for, the same pot can be used as volume or tone. What causes it to function as a one or the other is how it's wired in the circuit with capacitors, etc.
Here is a good grphic representation on the properties of auio vs. linear tapered pots. When you get to the page, click on Master Volume Mod and enjoy!