definitely give him a soak, and then try gently using a wash cloth. This always works for my sand boas when they have stuck caps.

Take a Q-tip and soak it with luke warm water.  Very gently dab the water on the eye.  Keep repeating, it will soften and loosen the eye cap.  Then very gently rub back and forth, the cap will slide off.  Just make sure you have moistened the eye cap several time.  Don't try to push off, when it is loosened enough it will slide of much like taking out a contact lens.  Have done it a few times and worked every time.

I would give it a nice long soak  and then use Lisa's method

Always a long soak, A tub with enough water to keep him wet.  Also put a wash cloth in there for him to rest on.  15 mins later it should slide right of.  Put to lid on it to keep the humidity high.  It has worked for me 100% of the time.  Good luck.

If the above methods don't work, do not try to force them off.  The snake could lose an eye if you get too forceful about it.  Wait until he turns blue again, and bump his humidity.  They could likely come off with his next shed.

Definetly listen to Skelegirl and don't try and force it off. I just took in a sand boa that is missing an eye from someone trying to force off the eye cap!

I adopted a ball python that had serious stuck shed including what looked like at least two stuck eyecaps. There were other issues with her including multiple mouse bites and a mite infestation. It only took three days to beat the mites. To get the stuck shed and the bites I put her in a small tote with aspen bedding, a hide, and a small water bowl. I misted the tote and got the aspen good and wet. I closed it up and placed it on an under tank heater. It was raining in the tote. The water would collect on the lid and fall back down. After two weeks he shed all the stuck shed came off and the mouse bites healed nicely. Two days later he ate. My nephew took him and he's doing great. Just another idea of something that worked well for me.

I have a sub-adult bull snake that always has trouble shedding her lens caps but was never fond of taking baths! I always kept a spray bottle handy and if I noticed that she couldnt shed her lens caps on her own, I would simply give her a good mist all over her head and body too. Usually after awhile of her rubbing against the substrate or rubbing up against herself the lens caps come right off :) Saves the stress of being soaked completly if they don't like that :p