I'm planning to make a posebox where only certain parts of the body are posed (legs, an arm, both arms, etc.), but I can't find any good tutorials on how to do this.

I already know how to make regular poseboxes, but I'm at a bit of a loss on how to make only certain parts of the body posed as an overlay, while the rest of the sim's body parts does whatever other animations. I'd like to know how to make the poses be prioritized over other animations, so they can be overlaid with other animations, like this one: http://www.modthesims.info/download.php?t=351524 and this one: http://deedee-sims.tumblr.com/post/...ere-most-of-the

I know I have to pose and set keys to only the parts I want to pose, but do I use the same export options as for regular full-body poses? And do I have to do something more to the actual posebox?

Isn't Deedee's posebox already an overlay one ? I think you just have to do alike, by observing it in SimPE.

I know I can do that - but I'm mostly wondering if there's something extra I have to do in Milkshape, like if the settings for the exported animations are different from regular poses, or which bones to set keys for (is it enough to mark the ones I want to pose and set a key for those, or do I have to select other bones as well?). Also, if I'm making poses for legs only, do I have to select anything extra from the list of bones and set keys for those as well?

Sorry I read you too fast and didn't see that you've already known about DeeDee's one. In DeeDee's posebox overlay, there're only one or some bones assigned, so you must do the same. However I don't know a thing about Milkshape...

Nevertheless, you can still remove those unwanted bones in SimPE afterwards :
1- In SimPE, select the bone you want to remove in the list of bones,
2- then right clik on the list of bones and select 'remove joint'.

Moreover, the bones aren't locked so they can be added to (modify a little) an animation playing. If you want the overlay to replace some parts of an animation playing, you must lock the bone (tick the box near the linear one, I don't know the name of that box in english, but in french it's something like 'parent' > for instance, see the 'root_trans' of DeeDee's legpose overlay). If you don't want a replacement, be certain that that box is unticked.

I'm just wondering if it's enough to mark and set a key to the bones I want to be posed (say, the legs, from perhaps the pelvis and down? I'm unsure of how far up/down I have to set keys for the legs to 'stick', and whether any the joints in the list in Milkshape have to be selected separately), then save the pose like you'd do with regular full-body poses, and then (if needed) copy the settings in the parts-poseboxes that already exist. Are there any particular things I'd need to do with the skeleton before saving (like which bones I must mark for it to work), or maybe save with a different setting for the pose/animation export, for instance?

Examples:
1: I've made a few chair-like objects that don't fit well with the regular chair poses. I'd like to make poses that locks the legs in place, while still allowing for the rest of the upper-body to move, kinda like Deedee's parts-poses for legs, and Decorgal's walking hack (makes sims appear to walk while they can do other things with their upper body).

2: I want to make arm poses for some sims that keep their arm/hand or arms/hands locked in place, while still allowing for animations for the rest of the body - something like the pose part of this box: http://www.modthesims.info/download.php?t=351524 or Deedee's arm/hand box.

I know how to make regular full-body poses and how to make poseboxes, I've just never done parts-poses that worked the way I wanted them to, so I'm curious if there are any differences.

As I can see nobody knows how to help you on that, you should test my idea (my previous post) or you've already tested it and it didn't work ? I am curious to know.