Aux-In on MY07 6 Stacker

[yumcha]

has anybody successfully installed the Subaru
Aux-In cable on the OEM 6 Stacker unit?
From what i read on other related posts
this should have nothing to do with the Sat Nav screen
however when i talked to Subaru Service today
they told me i needed to purchase a 'special'
cable which hooks up to the nav to enable the aux-in
...cost? $324 + labour.
i know theres a cable available from Subaru for $124
can anyone confirm if this is all i will need?