Very easy to do. Submit your review as always. Then, go to the bottom of your review, and hit the EDIT key. You have up to an hour I believe to edit any post you do. This applies to reviews as well as to any post you make.
There is one trick to watch out for. When you go to edit the review, you will see that the software has inserted a bunch of control characters to control how the review is displayed. These include private tags for the ROS, bold for certain parts, etc. If you screw these up or delete them, you can screw up your whole review.
If you screw them up, the MODs will have to fix it. In that case, you need to
(RTM) yourself and let the mods know you screwed up. They will berate you a little and fix your screwup.