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)