You can get what you want with some scripting. You enter text into a text field configured with an auto-complete enabled value list of the names, then a script kicks in and performs a find to locate the record in the related table, then brings the ID number back to the original layout and enters it for you. This script can even be set up to deal with duplicate names by bring duplicate matches up in a list where you can select one by clicking it to return to your original layout and enter the selected record's serial number.
That's one of 3 approaches for working with large value lists demo'd in this file: http://www.4shared.com/file/plr_jbkk/EnhancedValueSelection.html
This looks great, but I really need it to work in IWP. Is there something in the script that can be used instead on FREEZE WINDOW & SHOW CUSTOM DIALOG?
Thanks for you help!
Freeze window can just be left out in IWP or you can enclose it in an If step that skips it for IWP clients if you want to use the same script both with and without IWP.
In IWP, you can switch to a different layout or put text in a text field on the current layout to display the message from the custom dialog.