So I bought myself a yubikey and I plan to use it to create a more secure version of the main QT client whereby the regular passphrase prompt is replaced with a prompt for a one-time-password (OTP) authentication provided by the yubikey.

This will most likely require a custom built client. I can build QT on linux including necessary code changes.
There is also a yubico c library at https://github.com/Yubico/yubico-c

The question however is this:
Altough I'm somewhat familiar with the bitcoin client code, with the yubikey I'm starting at zero. What would, in your eyes, be the best way to approach this?

Has anyone attempted something similar?

Thanks in advance for any suggestions!