You must be S-Off for it to flash. Here is teh guide for How to S-off Verizon Droid Incredible 2: http://answers.downloadatoz.com/q,3033,how-to-s-off-and-root-verizon-droid-incredible-2.html
Note: Make sure you have Fastboot and ADB for Windows or Linux installed and have disabled your antivirus and firewall.
1. Download cwm-recovery-vivow.zip: http://forum.xda-developers.com/showthread.php?t=1134520
2. Power off your HTC Incredible S, turn it back on by holding Power button and Volume button.
3. Once its in HBOOT mode, press the volume up and down buttons to select "Fastboot" and use the power button to enter.
4. Now you are in Fastboot mode, connect the phone to your PC using the USB cable.
5. On the PC, unzip the recovery and put it in your Fastboot folder, once done, open open Command Prompt and cd into Android-SDK/tools folder (or the folder where your fastboot resides)
6. Type fastboot flash recovery
Once done, you have just installed custom Clockworkmod recovery.