The Samsung U740? No unfortunately not.
I have hacked the Motorola E815 and the HTC XV6800. I use the 6800 now. It is my pocket laptop so to speak.
I have not held the U740 but I know about the double hinge. It's a cool gimic if you ask me. If you can not load the ringtones via Transflash card you will need to use a USB cable and install them directly to your phone. Verizon is really good about neutering phones.
Anyhow do you have the USB cable that you will need to connect your phone to a PC?
If not here is a link from Amazon.com:
http://www.amazon.com/SCH-U420-SGH-D800 ... 101&sr=8-1
This program will help:
http://www.bitpim.org/
This one will have the windows drivers for your phone:
http://www.tian.cc/samsung_mobile_usb_4_40_7_0.zip
The Cable is like 2 bux on Amazon and as for the software it is all free if you follow the links.
Let me know if you have questions, I might be able to help more. Too bad you do not live down the street we could probably fix this in one afternoon.