I finally got around to getting this sorted out at the dealers. Afterwards I used VCDS to see what changes had been made to my 2010 S-Line Avant TDI:
[01 - Engine]
[Coding - 07]->[Long Coding Helper]->Byte 4, Bits 0-3 Changed from 0011 to 0100
[01 - Engine]
[Coding - 07]->[Long Coding Helper]->Byte 5, Bit 4 Changed from 0 to 1
(via check box "Trailer Installed" in VCDS)
[03 - ABS Brakes][Security Access - 16] (Enter code presented by program)
[Coding - 07]->[Long Coding Helper]->Byte 1, Bit 7 Changed from 0 to 1
(via check box "Trailer Hitch Installed" in VCDS)
[09 - Central Elec]
[Coding - 07]->[Long Coding Helper]->Byte 18, Bit 5 Changed from 0 to 1
(via check box "Trailer Hitch Installed" in VCDS)
[10 - Park / Steer Assist]
[Coding - 07]->[Long Coding Helper]->Byte 0, Bits 0-3 Changed from 0000 to 0001 [Trailer Hitch Not Installed to Trailer Hitch Installed (Manually Removable) via pull-down list in VCDS]
[5F - Information Elec]
[Coding - 07]->[Long Coding Helper]->Byte 10, Bit 5 Changed from 0 to 1
[19 - CAN Gateway]->[Installation List]->Tick 69 - Trailer
Hope this is useful to others!