s.a.,
The stock recovery is needed for the OTA to work correctly (although, if it failed once, it would also need to be manually applied after replacement of the recovery partition with the stock recovery). Replacing clockwork with Amon_RA won't get him what he wants, which is apparently the July OTA (or "back to stock").
Note also that if the PlainJane or Ivanmmj Official ROMs use the same init.rc scripts that the stock 2.1 HTC ROMs used, then the "One Click" or "Dummies" rooting methods will overwrite the recovery partition with Amon_RA. Think of it as "rooting root". That's sort of an easy way to do things that uses methods that are familiar to him/her.
There are three or four other alternatives: he/she can just install T2noobs "Plain Jane T2", using his/her existing ROM Manager/clockwork. It is based on the July 17 OTA, so it should work identically to the HTC (July 17 OTA) stock ROM.
If "back to stock" is mandatory, the easiest thing for him/her to do is flash the Leak-V3 PB00IMG.ZIP ROM. As soon as it starts up, it will recognized that the July OTA is needed; not only that, but it gets him/her back to 100% stock.
eu1