Strange their should be something in one of those two places.
Try deleting the app. it sounds like it's more than just a simple printer driver.
Most printers usually come with some lame extras. Like photo printing software. All of which you already can do with iPhoto
Have you been to their website. Do they offer just a driver?
Try deleting all software that came with it.
Take a look at the second link. Many of Brothers printers are already supported by leopard 10.5. No need to install any extra driver.
If You do need to install a driver. Just install the driver and nothing else. Do you have just a printer, or a printer/scanner?