I think it very much depends on where you are coming from and what routes you are on while on your way to Guad? I can't tell you much about what Guia Roji says as we find it to be almost useless. We use Microsoft Streets & Trips and Garmin.
Here is a route if you are coming from the east on 15D. There is an exit by Zula that goes south to Ocotlan - shows as 6 on S&T - about 30 miles east of where 80D connects to 15D - and about 25 miles west of where 110 comes down from Irapuato/Penjamo. From Ocotlan we take 35 west toward Chapala. 35 then meets up with 23 which is the Chapala road near Santa Rosa (about 30 miles) - you would have to retorno on 23 a bit north of there to go south to Chapala. Or you can go north on 23 a bit (couple miles) to 113 which takes you on the north side of Lake Cajititlan and over to 54D a little north of the turn to Villa Corona. This avoids all Guad traffic.
If you come down on 80D you can get on 80 and then take the road that cuts over toward the Guad airport and 23 - I am not sure if you can go south from here so you may have to make a retorno. Then take 23 south to 113 and across the north side of Lake Cajititlan over to 54D as before.
There are a couple of other routes depending on how familiar you are with the area. You can go through Chapala/Ajijic over to Jocotepec and up to Corona from there.
Ask me if you need more detail - or I can email you a map if you PM me.