Help Cannot change roms due to system recovery 3e


Hi. I have a HD2 with android already installed. I cannot however install different roms because I have Android System Recovery 3e. This 3e version does not allow unsigned roms to be installed. I have installed CWM but when I boot to recovery it still loads 3e. How can I install and access CWM so that I can install unsigned roms (I want to install Cyanogenmod).