[V8] Heater fan replacement

[Hoffman Anthony J A1C 552 CMS/MXMVC]

I am looking to replace the heater fan in a friends V8 (also mine but that
is later). He paid $2500 for the car, and does everything the "easy" way.
anyhow, he wants to use the "steak knife method". Has anyone seen this done,
and where would you cut the heater box for this method? Also, any hints on
doing the job right for my V8 (I'm replacing the fan, heater core, and valve
in mine)? I'll be doing it in a week or so.

Thanks,
Tony
1991 V8 pearl 270K
1991 VW Fox Unk