Have u looked at
Civ4BuildInfos.xml?
it contains the preqs for the building action for improvements, like for example the windmill:
<BuildInfo>
<Type>BUILD_WINDMILL</Type>
<Description>TXT_KEY_BUILD_WINDMILL</Description>
<Help/>
<PrereqTech>TECH_MACHINERY</PrereqTech>
<iTime>500</iTime>
<bKill>0</bKill>
<ImprovementType>IMPROVEMENT_WINDMILL</ImprovementType>
<RouteType>NONE</RouteType>
<EntityEvent>ENTEVENT_BUILD</EntityEvent>
<FeatureStructs>
<FeatureStruct>
<FeatureType>FEATURE_JUNGLE</FeatureType>
<PrereqTech>TECH_IRON_WORKING</PrereqTech>
<iTime>400</iTime>
<iProduction>0</iProduction>
<bRemove>1</bRemove>
</FeatureStruct>
<FeatureStruct>
<FeatureType>FEATURE_FOREST</FeatureType>
<PrereqTech>TECH_BRONZE_WORKING</PrereqTech>
<iTime>300</iTime>
<iProduction>30</iProduction>
<bRemove>1</bRemove>
</FeatureStruct>
</FeatureStructs>
<HotKey>KB_W</HotKey>
<bAltDown>0</bAltDown>
<bShiftDown>1</bShiftDown>
<bCtrlDown>0</bCtrlDown>
<iHotKeyPriority>0</iHotKeyPriority>
<Button>,Art/Interface/Buttons/Builds/BuildWindMill.dds,Art/Interface/Buttons/Actions_Builds_LeaderHeads_Specialists_Atlas.dds,5,8</Button>
</BuildInfo>
this may be what u're looking for, hope it helped

.