Rinse them off with cold water and trim off any offending little things you or don't like the looks of. Put in aluminum pan, cover with plastic wrap (this is your protection from squirting injection stuff)
Leave them in the cryovac ..and inject THROUGH the cryovac ..then after you inject them , remove from cryovac, lightly rinse pat dry etc.
Inject the meat every 1 inch or so , really pump it in there. Drain off excess injection in your pan. Liberally coat entire meat all sides with the rub. let sit ... one to 12 hours . I perfer one or two hours. Get pit to aprox 225 ti 250 deg. at grate . In the Big Green Egg I try to use 260 dome temp. Add wood chips, chunks, / etc. (I prefer Hickory)