Yes, it should work – you just need to know the settings that are configured on their existing device.
If you’re lucky, you’ll only need a username and password to put into the PPPoA settings – the rest should work with default settings. These may have been written out in a letter sent with the router.
I’m guessing that they already have broadband, and were provided with a small router/modem that’s connected to one PC with a USB cable ?
If you haven’t got the username and password, you’ll need to connect to the admin interface of the existing router and log in. The address will be something like 192.168.1.1, username ‘admin’. As for the password, they’re often shipped out with a factory setting, even something obviously like ‘admin’. See what the router is, try googling for the default IP address and admin username and password. Once you’re in, find the PPPoA username and password. If it’s got Wifi, you will be able to find the Wiki account details while there, and use these to connect a new wireless device.