To create gibs you need to use the spawngib command and possibly the attachmodel command. These need to be added to the necessary server section of the animation in the actors tiki file.
<frame #> spawngib <offset> <final pitch of gib> <size> <cap name> <list of surfaces>
ex. 0 spawngib "-10 -50 55" -45 15 cap_arm_right arm_right*
offset the center of the section being cut off (relative to the origin of the actor in this frame and animation)
final pitch how you want the gib to be rotated (pitch) when it lands on the ground
cap name the name of the cap inside the actor to hide the hole
list of surfaces all of the surface names that are going to be in the gib and no longer in the actor
Spawngib basically cuts off the section of the actor specified (list of surface names) and flings it a little ways (random distance), turns on the cap surface on the gib and actor so there is no hole created, and tries to make sure it lands at a reasonable angle.
NOTE: currently the gib should land at the specified final pitch or the final pitch + 180
<frame #> attachmodel <model name> <tag name> <scale> <target> <detach at death> <remove time>
ex. 0 attachmodel fx_bspurt2.tik tag_arm_right_high 1 "" 0 5
tag_name tag where you want the model to be attached to
scale scale of the attached model
target target name of the attached model
detach at death should the model be detached from the parent at its death
remove time how long it should remain
In this case attachmodel is just used to attach blood spurt models to the relevant parts of the actor. Detach_at_death should be 0.
A good example of both of these is the death_gib1 animation in creeper.tik.