There is no good way to populate scrolling windows. The issue is that Dynamics runs code behind the fields and thay they hold the field values in some sort of record set *in the form* that you can't get to - it's not exposed. For instance, in the SOP Transaction Entry window if you populate the quantity field, they want to look at the unit price field and update the extended price. You don't have access to all that code.
Some times what I want to do works, sometimes it doesn't. Depends on the form and the field.
You're 100% sure if you *close the form* and insert the data using eConnect.