MediaLab is not your best bet here. This would be a breeze in DirectRT--in fact you could use the simple "text.csv" sample that comes with DirectRT in the "samples/bare bones" folder. If you do not want a reaction to each word, just replace "rt:any" on each trial with "150"--voila! You can then embed that input file within your more general MediaLab experiment as a DirectRT "item" in your questionnaire.