Make a list that allows you to memorize the information in a virtual column. A list might include the things in the column in order, or might include details about the items that help you relate the column back to the information you already know.
Sometimes virtual columns lead to results. For instance, if the column is a list of computer code that creates a page, it might be easier to memorize what the page looks like so that you can memorize what the code must be that has created it.
Create a mnemonic device, in the same way as you would to memorize a regular column of information printed on a piece of paper. Come up with a word or phrase that uses the first letters of the pieces of information listed in the column and memorize that.
You can also memorize virtual columns by promoting a deeper understanding of those things inside of the columns. If you can understand what the columns mean, instead of just trying to memorize what they are, you might be able to remember specifics more easily. For instance, if you are able to understand a set of equations on a deeper level, it will be easier to memorize them in a virtual column.