Wifi is a totally different system to wired and quite a lot more complex - you might as well ask how you can convert a black and white TV into a colour one!
I've seen compact flash wifi adaptors for less than 15 quid on ebay, just be sure to get a prism chipset based one so WPA will work.
As for wifi access point, older ones which will only do 802.11b and not g or a go for less than 15 quid on ebay too.
Another cheap choice is to use bluetooth for the wireless link - I use it in preference to wifi as it also saves battery life!