How are REST Array Parameters handled over MultiPart Form and XMLRPC?

Question

Im using an API and one of the ways this API works is it lets you declare an array of parameters for some calls. The way they describe the rest request looks like this:

http://example.com/?params[]=option1&params[]=option2

This declares 2 array parameters in the array of parameters (option1 and option2)

How would these be sent over XMLRPC and POST Multipart? Right now I'm doing

<params>
  <option1/>
  <option2/>
</params>

but I dont think its working right.

For the Multipart POST i'm treating each one as its own parameter. So i'm sending 2 parameters with name params[] and one has value option1, the other has value option2. I dont think that is working right either.