In a saucepan over medium heat, add the ketchup, soy sauce, honey, mustard, sugar, garlic, and lemon juice. Bring to a simmer and cook gently until thickened, about 10 minutes. Set aside and cool. Take out half of your sauce, and use to marinade the chicken for 2-4 hours in your refrigerator.
Once the chicken is done marinating, heat up your grill. Cut chicken into bite size pieces. Peel the pineapple and cut it into 1 inch chunks. Take your skewers after they have been soaking in water for one hour, and begin adding the chicken and pineapple. Alternate between the chicken and pineapple when threading the pieces onto the skewers. Brush them with olive oil and season them with salt and pepper. Cook them on the grill, basting regularly with the left over barbecue sauce, until cooked through, about 10 to 15 minutes.