You need to share at least one item on each 98 unit and run the Network Setup Wizard that you made a floppy from when you ran it in the XP machine.
Provided the Wireless is working and configured properly it should be a simple matter to configure the LAN on a Simple Peer to Peer LAN. Just remember to enter the same Work Group name on each machine or they will each be in their own workgroups and not see each other.
Once this is done you'll need to go into the setup of the Wireless router and configure it to only allow these computers to access the Wireless connection or you may find that you have created a hot spot where unauthorized people can log onto the Internet through your Wireless connection and depending on your ISP contract may run up an excessive bill for you or do even worse things that could result in legal action against you.
If you currently do not have a wireless connection working you'll need to consult your wireless router manual and enter the Router setup procedure to make it possible to allow the machines to join in. Generally at the initial setup the connection is left wide open and then when the LAN is configured the Wireless side is tied down to prevent unauthorized access.
If you leave this as an open Hot Spot and someone downloads some Kiddy porn you will be responsible and will be facing the consequences for not securing your Wireless point properly.
This is a good case where an ounce of prevention is worth several pounds of attempted cure after the event.
Col