Nah that ends up either locking up on boot or having no apparent change iirc. Its also what happens if you drag and drop stuff directly to the NAND. I have gotten it to work with an old Proto Slim years ago but can't remember what I did beside just dropping the dash files into the NAND.
On 21256 recoveries, without an RGLoader Shadowboot, there seems to be something that either has a backup of the original dash.xex file and is either restoring that original file or is loading the backup directly. On 20353, dashboard refuses to start.
when I did it I was on 21256.3 and slapped in the NXE dash, try sending over only the main dash files, none of the guide/mini dash or anything else?