The "Penny Pinnacle rappel route" goes pretty much straight down to the notch between Penny Pinnacle and the main wall (4-5 70-80' rappels). Then slightly left down the south chimney approach to Penny Pinnacle (2-3 70-80' rappels).
The last rappel is on low angle ground with some loose rock (in the rockfall damaged area of Cathedral Chimney). The gully is wider there, so it does not seem as hazardous as the upper part (i.e. room to run away), but there is still some risk. There are also rappel anchors which go down the gully on the north side of Penny Pinnacle (aka "John's Other Chimney" in the Roper guide). This would completely bypass the Cathedral Chimney, but it would be longer.
The key to finding the top of the Penny Pinnacle rappel route is that it starts next to where the Alley Kat route tops out. Alley Kat is a big left-facing corner on the right wall of the Cathedral Chimney, left of Penny Pinnacle. There is a faint (and very exposed) trail straight down to this spot, and it is below where the Katwalk first hugs a 30' vertical cliff. There is also a big (100') fir tree about 50' above the Kat Walk at this point. The first rappel point is on a slender 30' double pine tree at the brink of the 450' wall. All the other trees in the brink area are live oaks, so it should be easy to pick out. The last 10' down to this tree is exposed 4th class. The first slings are orange and purple. Here is a full list of the anchors:
1. slender 30' x 8" double pine - at brink orange + purple slings, 2 rap rings 70' to next anchor 2. double live oak - in 3' corner (ant tree) yellow + olive drab slings, rings 60' to next 3. 3" manzanita + jammed knot - at stance, bottom of corner red + lime green slings, rings 60' to next (jammed knot could be replaced by a .75-1.25" wired nut) 4. fir + live oak under roof blue + olive drab slings, rings 75' to next 5. wired nut + 2" jammed rock - stance on left wall of corner pink + old yellow slings, rings 30' to next [can combine 4+5 with 60 meter rope, or if willing to downclimb easy ground] 6. live oak - in big corner yellow + blue slings, no rings 70' to next, + 20' easy 3rd class to big ledge at Penny Pinnacle notch some chance of rope hangup (chockstones in chimney; vector rope outward on last pull to avoid) 7. live oak - on south side of notch magenta slings, rings 60' to next (option here to climb 50' of 3rd class down northern gully and rappel it; one set of visible anchors there, and would require at least 2 rappels, possibly 4 or more) 8. sloping horn + 1" live oak (backup) - at top of chimney yellow + yellow slings, no rings 80' to next, down chimney 9. maple - at top of rockfall damage zone purple sling, no rings 70' to talus (or can downclimb loose/dirty 3rd class)