Depending on what version of EZ CD Creator you have, you should be able to select from the <FILE> menu, create CD from image. (or something close to that) From there select the ISO file and let it go. There should be no need to make it bootable, the files inside the image are set up for a bootable disk. If you have a newer version of Creator there may be a choice on the opening splash-type screen. If not, try selecting <Create a Data CD> and then looking under the <FILE> menu as above.
Hope this helps,