Something

roms[$cnt]="${line}.pce"
cnt=$(($cnt + 1))
done < "$1"

for ((i=0;$i<$cnt;i++))
do
#x="$x'roms/${roms[${i}]}' "

x="$x "'"`echo -n \"roms/${roms['"${i}"']}\"`"'

done

./ucon64 -multi=32 -pce -nhd pceboot.pce "$x" multi.pce