You could try booting into pure DOS and copying the files over to overwrite them, this should do the trick.

While using INF files was the normal method since Windows 2.x (or 1.x, even, but 1.x had very crude, static drivers) of installing new drivers,
it's possible to manually add them to system.ini (and win.ini) in Windows 3.x onwards
(Win95 uses registry but also supports the old system files, partly because of retaining compatibility to 3.1 drivers).

So if you know how these drivers are configured (as they are on another Windows installation), you can add them manually.
For example, these is are some parts that are altered by S3 graphics drivers (in Win 3.1):

//system.ini//
[boot]
386grabber=s3911grb.3gr
oemfonts.fon=vgaoem.fon
286grabber=vgacolor.2gr
fixedfon.fon=vgafix.fon
fonts.fon=vgasys.fon
display.drv=s3vsnd.drv
...
[boot.description]
aspect=100,96,96
displayinf=OEM0.INF
display.drv=S3 864 1.41B5 800x600 256 colors SF
..
[386Enh]
display=vdds3vsn.386
EGA80WOA.FON=EGA80WOA.FON
EGA40WOA.FON=EGA40WOA.FON
CGA80WOA.FON=CGA80WOA.FON
CGA40WOA.FON=CGA40WOA.FON
..
[DISPLAY]
dpi=96
color-format=8
screen-size=800
fastmmio=on
textrmw=0
scache=on
ellipse-support=on
polygon-support=on
dac-type=nbt
..
[s3_24.drv]
FontSize=small
WidthXHeight=640x480
..

//win.ini//
[drawdib]
vga.drv 640x480x4(0)=5,0,0,0
S3VSND.DRV 640x480x8(5)=1,0,0,0

Edit: A few typos fixed.
Edit: Text corrected.