It's a bit tricky and I cover it in great detail in my book (with a full example). I also have answered this elsewhere in more detail in other forum posts. So you can search the forum and find it somewhere in here. But here is the general idea.

You need to create two Global arrays in a formula and attach that formula to some non-necessary property of the cross-tab. In the book's example I used CSS Class Name property. Then in the formula you need to pull the data from the cross-tab as it is being generated and save it to the array. You can get the current value using CurrentFieldValue. Thus, you can save the Time In to the first array and Time Out to the second array.

The next problem is determing when the cross-tab is printing the first column or the second column. Use the function GridRowColumnValue() to get this data. Use it with an If-Then statement to decide which array to put it in.

yes, this is pretty complicated (it takes me seven pages to cover it in the book). But if you are experienced with formulas, you should be able to pull it off.

You can find out more about my books at Amazon.com or reading the Crystal Reports eBooks online.