I've just bought Lenovo R61 and have the same problem. In recent days I've tried ALL POSSIBLE solutions I could find on the internet, from the simplest ones to BIOS reinstallation - never worked. No "Stereo Mix", no "Line In", no "What You Hear" in Recording Options. Only stupid "Microphone".
Yesterday by accident I discovered, that by deleting "HKR,AD1984Disable, OutR, 1, 01 ;; Disable Stereo Mix Capture Node "
in the driver file called ADIHdAud.inf
and re-installing the driver I made the "Stereo Mix" volume bar visible.
Now, I have no idea yet whether this way will help me get other bars - have to de-cipher that code which I'm not familiar with. And also don't know if that works with my external USB sound card (E-MU 0202, I left it at home and will check in a few days). But that's the first thing that gave ANY EFFECT (contrary to all web-forums solutions), so come on guys, let's fix this crazy thing together!
EDIT: On a ThinkPad forum there's a long discussion on this issue, seems that simple ADIHdAud.inf modifications are not enought http://forum.thinkpads.com/viewtopic.ph ... sc&start=0