I just did this: took a 24/96 FLAC > converted to .aiff with foobar2000 > imported 24/96 .aiff into Audacity > changed **5** different settings in Audacity (changed track sample format from 32bit float to 24bit, disabled dithering, changed default sample rate to 96kHz, changed default sample format to 24bit, changed uncompressed export format to signed Microsoft 24bit WAV--which isn't immediately obvious, you have to select 'other' from the drop down box to access this option) > exported 24/96 WAV that can be encoded with FLAC Frontend or TLH. However, Audacity is changing the audio data somehow, because this exported WAV > encoded to FLAC DOES NOT MATCH THE ORIGINAL FINGERPRINT.

In other words, it's a real pain in the ass to do it with Audacity and will not yield bit perfect results. This is partly because Audacity is a fully featured audio editing/processing program. Foobar2000's conversion process, on the other hand, is elegantly simple. There are only a couple options, similar to FLAC Frontend: select FLAC level (1-8), replay gain processing (leave unchecked), DSP processing (leave unchecked), replay gain scan output files as albums (leave unchecked). And no audio data is changed in the conversion process with foobar2000.