What version of Vegas are you using?Batch rendering is a script included with Full versions of Vegas,scripting is not available in non Full versions.Also i beleive Batch rendering allows to render a piece to many different formats but NOT several clips.Maybe a script could be modified to use region rendering somehow.
There IS another way to do what you want but also requires the use of a FULL version of Vegas using"Network Rendering".
You aren't using it in it's intended use though to distribute complex long renders across mulitiple machines though.
You do NOT distribute network rendering.
This is handy if you have several projects and are going away on vacation or maybe in your case want to render a bunch of clips will at work.etc.
1)You will have to make a seperate Vegas Project for each song in your case by splitting and saveing just 1 track in each project.Do this for all the songs you want to render.
2)Open the projects minimizing or resizing the opened VEG projects so you can see and have them all open simultaneously on your desktop.
3)Go onto the Render as tab of each one and Tick on NETWORK RENDERING,but when the network render screen comes up DO NOT distribute network rendering.Do this for each project selecting your desired render formats and then Hit SAVE on each.Each project will render one after the other.Make sure you know where the renders are saving to.Good Luck!