Yes you can flash another recovery in recovery if you have the file in a properly zipped format. Which I just happen to have. Download the file below and put it where you can find it in recovery. Flash and you will have the cwm touch version on me.
Because they only provide the image. Recovery won't read img files. They must be properly put together into the correct package depending on the method of installation.
They understand the average user is not going to be able to install using the img and would prefer you using their rom manager app and get some of your money when you pay for the upgrade to touch.