There is nothing magic with the asset pack zip files. They're just asset directories zipped including the asset type parent dir, such so that a "mypack" asset pack with a "myclothing" clothes asset has a structure like
- Code: Select all
clothes/
myclothing/
myclothing.mhclo
myclothing.obj
...
All the install pack button does is to unzip the file in the user data directory.
So as jwc says, you can simply copy or download assets into that same structure, and MPFB will discover them when blender has been restarted.
If you have MH installed, you can also point out the MH user data directory implicitly or explicitly in the MPFB preferences in blender's preferences panel,.
But as this is bound to be a recurring question, I should really write some kind of tutorial for this.