The Get External Data tool remembers where your last navigation was to in v 2007, so I don't get why that doesn't help you, unless each import involves a different folder. Nor do I know what you mean by "in the settings". Settings where and for what? You can still set the default db folder, but I doubt that will help you much even if the files you want to import from are there also.
The import from file name is editable in the dialog if you're able to just get by doing that. If the file name has an easy to reference/change attribute such as "01" at the end, it should be an easy edit. Also, the specs are supposed to be held in two tables MSysIMEXSpecs and MSysIMexColumns. Even though I have an import spec in a test db and see all the other system tables, I cannot see those 2 even after closing and reopening. I tell you this because other methods involve vba to effect an import process; not sure if any of them pertain to changing the filename. You might want to investigate an update query to alter the file portion from a form and FilePicker Dialog if you can see those system tables.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.