did u mean u r using 4 pins of port 0 as input (with 0808) and 4 pins as output (with lcd),
if so, u can not do it coz port 0 pins allow either to be all inputs or all outputs i think.
u change to port 3 or port 1 in which all pins can be differently configured as input or output.
also whichever pin u want to use as input pin, make it internally high using program.
try it in ur project.