I found that icing was especially useful for treating tendonitis above the metatarsals. After two or three days of icing, I'd feel crepitus (creaking) in the tendons when flexing the toes up and down. To me, that indicated that the inflammation process had stopped. When the crepitus began to subside a bit, I could generally return to running.
Although playing around with shoe laces may help, I think this injury is usually a little more complicated than an irritation of the tendons caused by rubbing against the laces. I think it's more of an overuse injury. You can try various ways of running through it (for example, uphill treadmill running, which removes some of the stress associated with the eccentric contraction involved in lowering the foot to the ground), but the injury has to run its course.