Door jambs are one of my specialties

And there are many ways to go at them. I learned from Kevin Brown to use
Body Solvent for filthy jambs. This stuff cuts through grease and has a long dwell time. It gets hard to remove, though. I found FK1 #1119 does as good of a job, or better, and rinses much easier. Super Degreaser works for light dirtiness, but if you have some old caked on stuff it will require the heavy duty stuff.
3M Adhesive Remover works wonders, but expect to go through a can per jamb, so it gets expensive.
Process: I spray my product on a dry jamb. Use a brush (the 1" detail brush is my favorite), some old toothbrushes, etc. to agitate. Spray again, repeat. If the car is not too delicate, I will use the pressure washer to rinse off the product and blast away the grease. If you are careful enough you can keep almost all water from getting inside the car at full pressure (electric washer 1700 psi karcher with a fan tip). Nothing beats it! Once rinsed, I follow with more degreasers if needed, or a final cleaning with something like OPC or TAW, then another rinse. Blow dry the jamb, and get some spray wax in there, wipe off.
Search for some of our threads here, I'm not sure which one we have pics of us using the pressure washer right off the top of my head, but there should be a few.