my buddys got a scanner that'll read obd1 codes... how do i pull them from my 95 civic?

ive been throwing a CEL since i did my b20 swap around 3500 miles ago.. and it has a idle misfire issue that came around 2 weeks ago.. it seems to drive fine as long as your on the gas more than 10%.. but if you try to hold it at one speed it triggers the misfire and the car jolts like crazy.

things ive replaced recently:
distributor
cap
rotor
plugs
wires
TB and IM and valve cover gaskets
MAP and TPS sensors
fuel pump (upgraded to 255lph)

can anyone explain the process of reading obd1 codes.. or shine some light onto my idle problem?