How can we mix motions without Motion Director?
I have 2 motions that I need to blend together where a character is walking forward and then swings a weapon while he is still walking. 
The walk and the swing are 2 different motions. I need the swing to occur while he finishes his final 2 steps. I used to know how to custom import into the MixMotions tool but that seems to no longer be a feature.
Until we can custom import walk iMDs, how can we mix those motions together? 

You can start with those tuts:
https://www.youtube.com/watch?v=ZQ2fU6t7vMU
https://courses.reallusion.com/home/iclone/character-motions

My latest movie THE GOLDEN MAN, and a few others: https://www.youtube.com/channel/UCIl1EqVCKitZzLqaNnLK0BA

Yeah, I've looked all over those. I have to combine the two motions. I have to mask the upper body at a specific keyframe on one animation and remove the lower body from the other animation to combine the two into one clip. We used to have a MixMoves tool to do that with a long time ago but I'm assuming that motion director has replaced it as a far superior tool. The walk animation is very specific and cannot be easily recreated with the current walks within iMD. 
I thought that I could use Animation Layer to do it by converting each motion into keyframes, then deleting the base motion and combining the keys at the specific frame but this doesn't seem to work. I think its something that RL should work on though, it would be quite powerful if the keyframes could be retained and the base motion deleted.  

I am quite astute with blending and merging animations. Combining the animation through body masking and weighting is what I need. Any ideas?

Myself and others posted some routines and recommendation here: https://forum.reallusion.com/FindPost539994.aspx
and here: https://forum.reallusion.com/FindPost540591.aspx

Great tutorial. I trued this before and couldn't get it to work. I have tries it since watching your tut and iC8 keeps crashing. very frustrating.

This is what I need, but iClone crashes every time I try to cut/copy/paste. I even try frame by frame and it works for a few frames and then crashes. Its impossible to restore because frames will be missing. 
Have you successfully done this in iC8?

Have you successfully done this in iC8?         

Not after series of latest IC8 updates. Yes, I am struggling with copy/paste keys on timeline and Curve Editor myself in other projects and tasks. I hope they fix it soon.
https://forum.reallusion.com/FindPost557131.aspx

And BTW those 2 videos with Kevin were made in IC8 where I had no any issue. But that was a while ago before faulty updates.

I just tried a few times to combine motions in current IC8 by replacing a batch of keys for selected bones and it worked out just fine without a crash.
I also tried deleting an entire curve in Curve Editor and it was also stable. Maybe I was lucky or RL has fixed the issue in the latest update a day ago.

In IC7 I have shown to do the Sampling Optimized. But to be on a safe side, always sample full set of keys for selected bone.
Optimized does not work right for every other motion while replacing keys, probably because of different clip structure generated by IC8.

Here is one I just made in the latest IC 8.51.3501.1

Yes, it appears that the update fixed the issue. Thank you 4u2ges. I'll play around with this a little. Great tutorial and great information.