Number from portal records to appear in pop-up list?

[chrismarriott]

Is it possible to have information from a portal appear in a pop-up list in a field that is not in the portal?

IE: A line item number from a portal being put in a field for an external cost so the external cost can be referenced to its associated product? Having line item numbers appear in a list is way more secure for data entry than transposing them or even drag and drop.

Any ideas/help would be greatly appreciated.

Thanks,

Chris