There are a couple of options,
1. Solo. Just put them within "Look out sir!" range of a big block and also keep them in check with predatory fighter. This does has the risk of him being magic missiled/shot of the table, but the enemy has to focus it's attention towards him.
2. In a unit of skirmishers. This had several advantages, first off he is protected from (magic missiles and ranged attacks. Skirmishers tend to move forward, so the priest can act as a vassal for your slann. Greatly improving the range of the big frogs' spells. Predatory fighter is still an issue. Not a big one, but still.
3. In a unit of skink cohorts. 10 skinks can house 2 priests (1 on each corner). If you deploy them 10 wide, the area that will keep the PF-Saurus in check is also pretty large. Put a musician on these guys for rallying purposes..
This is basically a bunker for your priest(s). Say you buy 2 units of skirmishers and 1 unit of skink cohorts, you have great flexibility to where you want to put your priest. Against enemy ranged attacks: hide him in either the cohort or the skirmishers, depending on your Slann/tactics. If the enemy doesn't have many ranged attacks, go solo!
Those are the places I would put my skink priest in. They are all viable, it just depends on the situation and what you want to do with them.
You
could place them in a unit of saurus warriors...but that wouldn't be effective on any level
Hope this helps,
The Hunted