I seem to recall that there was a feature added to Hijack which would switch to the aux-in when the mobile phone mute line (green wire on the empeg sled's wiring harness) went high.

This isn't a specific hijack feature, it's just one of the many things possible with IR macros. The mute line can be remapped to anything, mine just switches to AUX and back. Voladjust can then be used to even out the volumes of everything so it all sounds just right.

Matthew