"Is it possible to continue to connect by wire, as before, whilst installing the router for wireless access by the laptop? If so, how is it done?"
I've read that through three times and I still don't quite get your meaning. So I'll just explain how a router must be configured and hope that it answers your question.
When you configure a router or modem/router for the first time - regardless of any wireless capability - you must connect it to a desktop or laptop PC via an RJ45 Ethernet patch cable.
The wireless link cannot be accessed until it is configured.
Whenever you need to make changes that relate to or affect the wireless link, you must disconnect any wireless clients and enter the router's config interface on a wired PC again.
In other words, you must have Ethernet capability on at least one desktop or laptop in order to use a router.