A lozenge is nothing but content wrapped in a box with background color.
Simple text lozenge:
## Macro title: loz
## Macro has a body: No
## @param text:title=Text|string=string
## @param color:title=Color|type=string|required=true|default=#0000ff
## @param textcolor:title=Text Color|type=string|required=true|default=#ffffff
<span style="background-color:$paramcolor; color:$paramtextcolor; border-radius:3px; padding:0px 3px 2px 3px">$paramtext</span>
Make sure to select "No macro body" in the "Macro Body Processing" section.