1. Okay... Well I've never setup Internet Connection Sharing (ICS) on a "wireless" connection; but I think it will work.
2.
Crossover Cable. You'll need a "crossover" ethernet cable to connect the laptop computer to the desktop through their "wired" network connectors. I'd configure the laptop computer for ICS before physically connecting the two computers together.
Hold both ends of the CAT-5 cable together, tang side down. Now closely examine the color code (solid or stripes) on the eight wires in each connector. If the wires at each end of the cable are in the same color code sequence, you have a "straight through" cable. If they differ, you probably have a crossover cable.
Note: It's supposed to be a "crossover" cable, but if one or more of the network adaptors has
automatic crossover implemented and enabled, a straight through ethernet cable might work.
3.
Reference(s). For the documentation in the following links, the laptop will be the "host" ICS computer and the desktop will be the "client" ICS computer.
a.
Internet Connection Sharing (ICS) in Microsoft Windows b.
ICS Host Computer Setup in Windows XP c.
ICS Host Computer Setup – Windows Vista d.
Internet Connection Sharing – ICS Client Computer Setup4.
Satisfaction Not Guaranteed. If you successfully enable ICS through the "wireless" adaptor of laptop, the laptop must be on for desktop internet access and you'll be limited by its processing power, processing load, and the throughput rate of its "wireless" connection.
Although you should be able to "surf" the internet and perform "normal" downloads through the ICS connection, there are functional limitations that a normal connection doesn't have. I just don't remember what they are...