While the CUWiNware software will operate on most 486 or better platforms, most old consumer-grade 486 and original Pentium desktop machines have such old motherboards that PCI Wireless NICs or PCI/PCMCIA bridge cards will not function properly. Check to see if your wireless card requires PCI 2.0 and, if so, whether the motherboard of the desktop you are using has a PCI 2.0 compliant motherboard.
Your options for a wireless NIC are to use a PCI wireless card, a USB wireless card, or a PCI/PCMCIA bridge card with a PCMCIA wireless NIC. It is probably easiest and cheapest to find a compatible PCI card.
It is easiest if the BIOS on your low resource node supports booting from CD-ROM. Some very old motherboards do not support this. If you can't boot from CD-ROM, it is possible to bootstrap with a special floppy disk which will then hand over control to the CD image.
An attic-based node will probably not have a keyboard attached to it. You'll want to disable the requirement in the BIOS that a keyboard be attached. Otherwise every time the node is turned off and back on it will hang on boot while it waits for a keyboard to be connected.