Actually Ed you do not even need that missileobject.ini anymore. At the bottom of the weapon that has WP just add this
[WeaponData001]
TypeName=Mk40_Hydra_Mk67mod0
FullName=2.75" Mk 40 Rocket (White Smoke) w/Mk67 MOD 0
ModelName=Mk40_Hydra_Mk67mod0
Mass=11.11
Diameter=0.070000
Length=1.440000
SubsonicDragCoeff=0.200000
SupersonicDragCoeff=0.370000
AttachmentType=
SpecificStationCode=
NationName=
StartYear=0
EndYear=0
Availability=0
BaseQuantity=0
Exported=FALSE
ExportStartYear=0
ExportEndYear=0
ExportAvailability=0
WeaponDataType=1
RailLaunched=FALSE
RocketPod=TRUE
Retarded=FALSE
FinStabilized=TRUE
SpinStabilized=TRUE
HasGrowl=FALSE
EffectClassName=WPRocketEffects
ReleaseDelay=0.000000
WarheadType=0
Explosives=0.000000
FusingDistance=0.000000
ClusterBomblets=0
ClusterDispersion=0.000000
GuidanceType=0
Accuracy=70
MaxTurnRate=0.000000
MaxLaunchG=2.500000
LockonChance=0
LaunchReliability=70
ArmingTime=2.000000
SeekerFOV=0.000000
SeekerGimbleLimit=0.000000
SeekerTrackRate=0.000000
SeekerRange=0.000000
CLmax=14.000000
MinFreq=0.000000
MaxFreq=0.000000
MinLaunchRange=0.000000
MaxLaunchRange=0.000000
Duration=60.000000
CounterCountermeasure=20.000000
NoiseRejection=20.000000
CapabilityFlags=0x00000000
LoftAngle=0.000000
DescentAngle=0.000000
MaxLoftAltitude=0.000000
BoosterStart=0.000000
BoosterDuration=1.700000
BoosterAccel=122.449997
BoosterEffectName=RocketFireEffect
BoosterSoundName=Rocket
BoosterNodeName=
BoosterPosition=0.000000,-0.730000,0.000000
SustainerDuration=0.000000
SustainerAccel=0.000000
SustainerEffectName=
SustainerSoundName=
SustainerPosition=0.000000,-0.730000,0.000000
InFlightEffectName=RocketInFlightEffect
InFlightSoundName=
ReleaseAnimationID=1
ReleaseAnimationTime=0.500000
ReleaseAnimationDelay=0.000000
EODisplayFlags=0
CEP=10.000000
[WpRocketEffects]
EffectShaderName=twColor1.fx
GroundHitEffectName=WilliePeteGroundExplosion
GroundHitSoundName=SmallExplosion.wav
WaterHitEffectName=MediumRocketWaterHitEffect
WaterHitSoundName=
ObjectHitEffectName=WilliePeteGroundExplosion
ObjectHitSoundName=SmallExplosion.wav
ArmorHitEffectName=MediumRocketAirExplosion
ArmorHitSoundName=SmallExplosion.wav
CraterModelName=
CraterType=1
Add the bolded portion and provided you have that effects in your effects folder it works.