There's a few different routes you could use to complete this task. The first and most powerful way to go would be through a custom item. Custom items however have a higher learning curve than the other item types available from within MediaLab.

For more information on custom items, see the following link:
http://www.empirisoft.com/medialab/h...stom_items.htm

By utilizing the power of HTML and Java, you can create tools similar to the example provided in the following link:
http://www.empirisoft.com/support/showthread.php?t=540

Through the power of custom items, you could also create a list of items to be checked off from within a list. See the following link:
http://www.empirisoft.com/support/showthread.php?t=825

The second route you could head in would be through utilizing the power of the 'ranking' item type. The ranking item type could be used so that the user lists each item in a manner that they feel indicates a 'gradient' of similarity. The only problem with doing so is that the ranking feature only supports 12 items to be used at a time.

You may also want to try using the 'Essay' item type. The essay item type will allow for the user to list the items in any order or grouping manner that they like. If you do not have enough room to present each item that the user can select, you may want to have MediaLab open a Read Only notepad file and present it next to the MediaLab window.

Let me know if this helps out.