I can't find any information relating to VCP from Microsoft directly but it seems that VCP has been out for a while. Its available for direct download from here:

winxpvirtualcdcontrolpanel_21

Inside the self extracting archive are 3 files:

readme.txt
VCdControlTool.exe
VCdRom.sys

The readme for the application is pretty straight forward, within a few steps you should be mounting and unmounting ISO image files from your virtual cd drive. The instructions say to copy VCdRom.sys to your %systemroot%system32drivers folder, but I found that when you browse for VCdRom.sys using VCdControlTool.exe it actually doesn't matter where it is. Here are the instructions from the readme anyway:

Installation instructions
=========================
1. Copy VCdRom.sys to your %systemroot%\system32\drivers folder.
2. Execute VCdControlTool.exe
3. Click "Driver control"
4. If the "Install Driver" button is available, click it. Navigate to the %systemroot%\system32\drivers folder, select VCdRom.sys, and click Open.
5. Click "Start"
6. Click OK
7. Click "Add Drive" to add a drive to the drive list. Ensure that the drive added is not a local drive. If it is, continue to click "Add Drive" until an unused drive letter is available.
8. Select an unused drive letter from the drive list and click "Mount".
9. Navigate to the image file, select it, and click "OK". UNC naming conventions should not be used, however mapped network drives should be OK.

Here is how I used it:

To remove/uninstall the CD-Rom driver do the following:

VCP worked well for me, it allowed me to install my program from ISO, I could even 'eject' or unmount the ISO that I had mounted in order to mount another halfway through the program I was installing (it was a 2 CD/ISO program). I've tested VCP on both Windows XP and Vista. It worked flawlessly on both operating systems and served it's purpose of letting me install from an ISO without having to restart my workstation after installing the driver. The best point of all though- its free.