Currently -
No
In the future, when the ASM to XML tool becomes available for SR4 -
Yes with a lot of effort on the older SR3 items, but alas
No on the SR4 unique costumes.
After the SDK comes out and things can be broken down and built individually,
probably for the SR4 unique costumes (but it will be ALOT of work).
The thing is...
In SR3 those individual files had a corresponding *.cmoprh (morph file) and *.str2_pc (contains the morph, mesh, and textures).
Currently we can take the SR3 smaller items that are not in SR4, unpack the SR3 *.str2_pc and repack it with the same name as an SR4 *.str2_pc. And the *.cmorph looked to have stayed the same format so no work is needed on that file.
The problem is the *.ASM file (this file tells the game what goes where)...
We can currently
update the SR4 *.asm files, but we
can not add to an *.ASM file.
The smaller (missing) items from SR3 will have to be added to the SR4 *.ASM file to work in SR4.
The same goes for the SR4 unique costume parts if they are ever broken down, those items with have to be added to the *.ASM file.
And yes the file extension may be the same between SR3 and SR4 but the *.ASM file type is different (just enough so the SR3 toolkit crash's when trying to read the SR4 *.asm file).
So clothing items from SR3
should be in the near future.
But the SR4 Unique items like the Female President suit, Rainbow Rider, and Uncle Sam are going to have to wait.
Oh and since I don't create the tools,
I can not give you a time line on what Near Future means.... could be a week, a month, or sometime in the 22nd century