The most conservative (perhaps best) choice is to not dive.
If you insist on attempting to dive, then equalization will probably be your main concern. You should worry about ear equalization and sinus equalization. You may want to give Neti-pot (saline irrigation) a try. The saline acts as a mild decongestant. Oral OTC decongestants such as pseudoephedrine might also be helpful. You may want to try the nasal spray Afrin (oxymetazoline). Be sure not to take Afrin for more than three days.
Whatever you try, make sure that the stuff doesn't wear off in the middle of a dive...or else you could be in a world of hurt. Also, be aware of any potential interactions between the decongestant and whatever else you are taking (prescription meds, seasickness meds, etc.).
Be prepared to descend very slowly. Head colds are often associated with sinus squeeze, so don't be surprised if you get an ice-pick-to-the-forehead sensation during descent. This assumes that you are able to equalize your ears. If either equalization of the sinuses or the ears is problematic, then you should thumb the dive.
You should know that lung infections can create a dangerous situation for divers due to the increased risk of pneumothorax and/or arterial gas embolism. The mechanism for this involves mucus accumulation which creates an obstruction in the respiratory system.
Anecdotal reports raise the possibility that viral infections can increase the DCS risk. If you plan to dive, dive extremely conservatively.
Good luck.