If there is no /system/lib/modules/ folder that means that ROM doesn't support external kernel module (CMIW). You still can use WiFi, but you have to load wlan.ko module manually.
1. Place wlan.ko to someplace. Ex, to /system/lib/modules/wlan.ko
2. open terminal emulator
3. type "su" (without quotes). grant permission
4. type "svc wifi disable"
5. type "insmod /system/lib/modules/wlan.ko"
6. Done. Your WiFi should work
don't forget to replace ramdisk and dt.img by these steps :