The actual mileage via the road is more like 20mi RT, not 25mi. This can be made shorter by using the nicely maintained use trail (unmarked) that starts at the junction with Main Divide Rd and traverses up and across the West Face of Modjeska. Saves almost a mile, each way.
Edit: I just realized this route is attached to both Santiago and Modjeska. Perhaps some wording can clarify the difference. May not be necessary since I'm probably one of the few clowns to hike up there only for Modjeska. :-)
What are doing in my backyard without calling me first? Bob, The guy who did the Modjeska page asked if he could borrow my stuff from Santiago. I never QCed his work. I used milages from Ken Croaker's Santa Ana Mountain Trail Guide (page 30 of 3rd edition which lists 12.5 to the top by road and verified by mountain bike odometers that came in just short of 12.25. Scott