Hi Jeff,
Thanks for utilizing the forum! FYI I also asked this question somewhat differently if you want to take a look at the responses.
In addition to the answer in the other thread, if you only need a simple GUI, with just textboxes as input, the answer lies in your question. Just model Table, Row, Column and Cell objects. Note that there are some plans for a spreadsheet like widget based on the domain model. If you are interested in that, just contact Johan for the schedule.