Here is the code from Tiberian Sun, I'm not sure if the locamotor will work in RA2, but you can try.
[VISC_SML]
Name=Baby Visceroid
Image=VISSML
Nominal=yes
Insignificant=yes
Strength=200
Category=Soldier
Armor=light
TechLevel=-1
Sight=0
Speed=8
Owner=GDI,Nod
AllowedToStartInMultiplayer=no
Cost=1
Points=50
ROT=16
Explosion=DIRTEXPL
MaxDebris=0
TiberiumHeal=yes
Locomotor={4A582741-9839-11d1-B709-00A024DDAFD1}
MovementZone=Normal
SmallVisceroid=yes
ThreatPosed=5
ImmuneToVeins=yes
[VISC_LRG]
Name=Adult Visceroid
Image=VISLRG
Insignificant=yes
Nominal=yes
AltImage=VISLGATK
Strength=500
Category=Soldier
Armor=heavy
TechLevel=-1
Sight=0
Speed=8
TiberiumHeal=yes
Owner=GDI,Nod
AllowedToStartInMultiplayer=no
Cost=1
Points=50
ROT=16
Explosion=DIRTEXPL
MaxDebris=0
Locomotor={4A582741-9839-11d1-B709-00A024DDAFD1}
MovementZone=Normal
LargeVisceroid=yes
ThreatPosed=20
Primary=SlimeAttack
GuardRange=5
ImmuneToVeins=yes