I know this thread is old, but I thought I'd add my experiences for others that might find the thread and want to try it.
I first did as
jkind did, but although it worked, I found using the wire wrap wire unnecessary. Also by just stripping the end of the RG174 to either 6.25 cm or 12.5 cm and taping or as I did Hot Gluing the one end to the GoPro rear door, and taping the other end to the iphone, ipad or other wifi device, it works a bit better.
Here is another 'how to' I ended up following.
http://paulillsley.com/GoPro_Underwa...tup/index.html