Hi nthere9,
As you have mentioned you are able to read name. If so, changing should also be easy one just assing the other string (refer to ActionScript Access to XMP Metadata section Manipulating metadata/Working with simple properties).
For reading the struct/array you have to first read the struct/array and then again iterate it. Please refer to ActionScript Access to XMP Metadata section Iterating XMP properties page 14.
If you still face any issue, please send me the code which you are using to read.