I don't think that was what he was asking. If the wings sweep on an aircraft at all, then most likely there is an animation slot added by the modeler in 3DS Max. The action of the wings sweeping in the Thirdwire series doesn't really make a difference to the flight model, as the series does not support different flight characteristics at variable geometry phases of the wings. See, if you take a look inside the data.ini of one of the aircraft, or any sweep wing aircraft for that matter, there should be an animation ID that is linked to a swing wing 'component.' For simplicity's sake, this component is usually set as a highlight device, allowing it to automatically sweep as velocity increases or decreases past a certain point. Take the third party MiG-27D mod for example, what you could probably do to make it a manual operation is change the current wing sweep data entries...
[LeftSwingWing]
SystemType=HIGHLIFT_DEVICE
DeploymentMethod=AUTOMATIC_MACH
Setting[1].Angle=45.0
Setting[1].DeployValue=0.80
Setting[1].RetractValue=0.85
Setting[2].Angle=72.0
Setting[2].DeployValue=0.40
Setting[2].RetractValue=0.45
MaxDeflection=72.0
MinDeflection=0.0
ControlRate=0.2
AnimationID=1
CLiftdc=0.0710
CDdc=0.0200
[RightSwingWing]
SystemType=HIGHLIFT_DEVICE
DeploymentMethod=AUTOMATIC_MACH
Setting[1].Angle=45.0
Setting[1].DeployValue=0.80
Setting[1].RetractValue=0.85
Setting[2].Angle=72.0
Setting[2].DeployValue=0.40
Setting[2].RetractValue=0.45
MaxDeflection=72.0
MinDeflection=0.0
ControlRate=0.2
AnimationID=1
CLiftdc=0.0710
CDdc=0.0200
To something like
[LeftSwingWing]
SystemType=ANIMATION
InputName=ANIMATION_1
DeploymentMethod=MANUAL
AnimationTime=6.0
AnimationID=1
CLiftdc=0.0710
CDdc=0.0200
[RightSwingWing]
SystemType=ANIMATION
InputName=ANIMATION_1
DeploymentMethod=MANUAL
AnimationTime=6.0
AnimationID=1
CLiftdc=0.0710
CDdc=0.0200
Only problem with this is you would not get the intermediate wing sweep angles of 45° and 72°, however, you can see that manual wing sweep is possible.