Sorry there is no guide, but! There is enough info in the guides to get you to both boards. Follow this guide to get the cover glass off [https://www.ifixit.com/Guide/iMac+Intel+24-Inch+EMC+2134+and+2211+Glass+Panel+Replacement/8962}|2552762]
Keep in mind these are the only Bluetooth and WiFi adapters that will work in your system:
* [product|IF185-121|802.11n Airport Extreme Card, Apple P/N 661-4460]
* [https://www.thebookyard.com/product.php?cPath=34_164_174&products_id=2624|iMac Intel, PowerMac G5, & MacPro Bluetooth board, Apple P/N 922-8233]