One of the ferals i care for cam up to the door and had blood all over his face and was limping. its the only one that wont come near me. i was to catch him to take him to the vet. how would i catch him?
Can you borrow/do you have a humane trap? (Have you TNRd before?) Refrain from feeding him and hope he goes into the trap.
If you can't get near enough to him to scruff, that's about the only way you can get him to the vets.
Limping doesn't bother me as much as the blood on his face; is he neutered? May have gotten into a fight. Should have him tested for FIV/FELK (but know first the policy of the vet you'd be taking him to).
A trap is usually best here - ie the only possibility.
But if he come to your door, it may be he feels he does needs help, and he recognizes you are the one who may give him help. So he asks you.
In that case you can perhaps manage to scruff him and wrap in a thick towel... for transport to vet.
If so, try to foster him during his reconvalescention. He will be quickly socialized in such a circumstance.
You can try him also if you took him with a trap. Fostering when they are hurt quickens the processe.
But if he REALLY did come to you to seek help, and accepts to be catched by scruffing/towel without big fuss - then you are sure for quick socialization. Not years but perhaps even just weeks.
Scruff then immediate Cage or carrier. Have a carrier ready outside so you can transfer as quick as you can catch her. If s/he comes close enough for the scruff and you can grab quickly and stuff her in an open cage or carrier. Like someone else mentioned above, a cat "on the mend" I found will quickly socialize.
Look for local TNR groups for your town perhaps they can help trap if you don't have another way?