The most capable system available back then was the IBM Composer. This source took the work of a Composer expert and compared it to the bogus memos. Read what was required to get the results, and even they didn't completely match the memos.

Considering that the Composer's price, when adjusted for inflation, was approximately $20,000 in today's money, the chances of a Texas ANG unit having one is very, very slim. The chances that a man who didn't type (according to his wife and son) would use such a system to type some simple memos are even slimer. Even CBS's sources are backing off from the documents.