Hi Elf
I don't remember exactly how I did it. This is what I have
<option name="isConstruction" value="true"/>
<option name="constructionType" value="bunker"/>
<option name="constructionsPerTerrPerTypePerTurn" value="1"/>
<option name="maxConstructionsPerTypePerTerr" value="1"/>
<option name="canDieFromReachingMaxDamage" value="true"/>
and I think you need this property too
<property name="Place in Any Territory" value="true" editable="false">
<boolean/>
</property>
there might be some others needed too