Help with UI++ setup

Good Morning,
  I am trying to do some minor changes to a UI++ setup that was originally created by another tech.  Our current SCCM image was setup for the US, and I am trying to set it so that users can choose to setup windows for the UK.  I have tried to add a few variables that I THOUGHT were what was needed but had no luck.  Here are the relavant bits of the xml file.

<Action Type="Input" Name="LocationChoice" Title="System Location">

<ChoiceInput Variable="MyLocation" Question="Please choose a user location for this computer:" Required="True" ShowBack="True" >

<Choice Option="1 North America" Value="US"/>

<Choice Option="2 Europe (UK)" Value="UK"/>

</ChoiceInput>

<!-- ***** Set TSVars for OSD TS from input above ***** -->

<Action Type="TSVar" Name="OSDTimezone" Condition='"%MyLocation%" = "US"'>US Mountain Standard Time</Action>

<Action Type="TSVar" Name="OSDDomainName" Condition='"%MyLocation%" = "US"'>domain 1</Action>

<Action Type="TSVar" Name="OSDTimezone" Condition='"%MyLocation%" = "UK"'>GMT Standard Time</Action>

<Action Type="TSVar" Name="OSDDomainName" Condition='"%MyLocation%" = "UK"'>Domain 2</Action>

<Action Type="TSVar" Name="OSDTimezone" Condition='"%MyLocation%" = "UK"'>GMT</Action>

<Action Type="TSVar" Name="Region" Condition='"%MyLocation%" = "UK"'>EU</Action>

<Action Type="TSVar" Name="LocationCode" Condition='"%MyLocation%" = "UK"'>Lon</Action>

Are these even the correct variables to change? 
Is there a list of all variables that UI++ can alter?  
I know I really need to do a lot more reading on UI++, it is an awesome program, unfortunately I am in a time crunch and any and all help would be greatly appreciated.  


Josh