In Osmosis, can I combine key from one tag and value from another into one tag

I have some external data which I've converted into .osm format, resulting in the following:

          <tag k="Mode" v="highway" />
          <tag k="Type" v="primary" />

which I'd like to turn into:

          <tag k="highway" v="primary" />

(Before anyone asks, this is not for data that will result in any kind of importing into OSM! Am merely using the OSM toolchain, but with data coming from a shapefile.)

I can't work out from the Osmosis Tag transform documentation how to do this, if it is even possible.

I suppose I am thinking something along these lines, but this doesn't work:

      <translation>
        <name>Convert from Shapefile headings to OSM key-value pairs</name>
        <description>-</description>
        <match type="way">
          <tag k="Mode" v="(.+)" match_id="kv" />
          <tag k="Type" v="(.+)" match_id="kv" />
        </match>
        <output>
          <copy-unmatched />
          <tag from_match="kv" k="{1}" v="{2}" />
        </output>
      </translation>