You can set the "form" to be used for Insert, Change and Delete separately.
(See the button settings on the browse.)
"Selecting" from a popup though isn't going to "Insert" a record. You'd need to code that.
Frankly, I'd create a simple Form on the table, with just the one field (the lookup browse), then in ValidateInsert I'd add code o prime the record with whatever values you are choosing, and let it add the record.
that seems like the simplest architecture to me.
Bruce