How do you get it into the mechanism though?
using a light oil (like mentioned), just put it near the edge of mechanism and manually "ratchet" the wrench. It will go in with a little effort.. I do *not* recommend putting it on there and using any sort of air blast. Light oils will seap into the crevase just fine, but not grease (which you don't want in there anyways)
It's messy, but it's an easy way to do it and will keep them functioning for a long time. Sure, you use a bit more than you want to but the other option is an unlubricated (or not lubed enough) ratcheting mechanism, and we all know how those fare over time.
Another option is to use a cup of oil and submerge the racheting edge and then do the same as above, move the mechanism. Take the wrench out and thoroughly wipe it down. Oil will still be coming out of there for a while but again, it beats having nothing in there.
Oh, and an aerosol-style can of lubricant should be able to get in there as well without much trouble. Point and shoot.
However, some believe that they don't really need it and only do so when the wrench jams, which is a bit lazy IMO.