Here's a tough one for ya... Scrollable tables with locking cols/rows

I’ve got this tool, that has a ‘workbook editor’, which is sort-of like a simplified spreadsheet editor. Within this tool, I’ve got this table with a massive amount of editable tabular data inside of it.

Currently, I’ve got the entire table inside a div with the scroll set to overflow. Unfortunately, this causes a number of problems…

The main concern for our marketing department (the people who will be using the tool on a regular basis) is that when you end up with a good number of columns and rows, it’s difficult to edit the schedule, because you can’t maintain a view on thee 4 left columns and top row (which include the labels they use when entering data).

The solution seems to be to allow them to lock a variable number of columns and rows of the table, so they will always be visible upon scrolling. Unfortunately, the only few solutions I can come up with are very hack-happy and will require a performance degrading amount of JavaScript to complete.

Question: What would be your best, most efficient solution to this problem?

(The kick-off meeting to hand over the tool is tomorrow morning, so I need to wrap this up today. Any help is greatly appreciated. Thanks! :)…)

Screenshot of the interface - http://dl-client.getdropbox.com/u/18386/screenshots/vb.jpg