The link appears to be for the later model LS on the 1993/4 model you need to pull off the passenger side kick panel below the glove box ( it has a footwell light fitted into it so disconnect the bulb holder by twisting and pulling).
Put the passenger seat in the fully reclined position and lay with you head in the foot well,look up and you will see a black plastic box with 2 wing nuts on it,remove the wing nuts and pull off the bottom panel, reach in and remove the filter(s).
For some reason mine has 2 fitted in the box but this may be because it is an import,have a good look with a torch to see if yours is the same.
Make a mental note which way around the filter fits.
At over £40.00 from Lexus I have removed mine twice and washed them in soapy water,rinsed,allowed to dry naturally,sprayed with air freshener and refitted.
Also buy yourself an Air Conditioning aerosol cleaner to disinfect the AC system but bear in mind with the current low temperatures the AC may not kick in.