Your phone is rooted?
You need root explorer or other app with root access to your filesystem
mount system r-w
go to /system
change name recovery-from-boot.p to recovery-from-boot.p.backup
go to etc folder in /system
change name install-recovery.sh to install-recovery.sh.backup
If you don't have recovery-from-boot.p and install-recovery.sh. Try to flash other oficial stock rom without brand.
If you have those files and if you change name recovery-from-boot.p and install-recovery.sh reboot your phone to download mode and flash again recovery.
Had both those files. Renamed them. Now CWM installed fine
Any idea why I had so much trouble installing it?