Hi,
I 've found another patch applied by slimdevices for SqueezeCenter (the same resource from which the "support reading from stdin" patch originates) which adds support for seeking and decoding ALAC to the faad frontend:
http://svn.slimdevices.com/slim/7.6/trunk/vendor/faad2/seeking%2Balac.patch?view=markup&pathrev=30642
Add seeking and ALAC support in the faad frontend
Updated URL:
https://github.com/Logitech/slimserver-vendor/tree/public/develop/faad2
Looked deeper into it and I believe it breaks aac stdin funcionality, not to mention it can't really be applied (lots of rejected chunks).