I commend your desire to help however if you are not already attached to an NGO who has resources and experience in country then you risk becoming a burden.
My company is running supplies from the DR to PAP for our staff and families and every trip from SD to PAP we are being burdened by well meaning volunteers. The reality is once they arrive in PAP they have no plan, lodging, means of transport or any real knowledge of what to do or where to go and then we end up having to support them!
Security: It is becoming increasingly dangerous at night. Two days ago we had a Landcruiser stolen at gunpoint at 5pm at Croix de Bouquet which is an area that you will have to pass on your way into PAP from Jimani so plan to be through that area early in the day no later than 3 or 4pm because you will still have about 2 hours travel due to the congestion to get to Petion Ville before dark. It is relatively safe up in Petion Ville. However it is imperative that you have a secure location for your lodging sorted out prior to arriving in Haiti so that you are not on the streets at night and you have somewhere to secure your pack/bags during the day.
Please don't come across on a Scooter, if the supply convoys don't run you over then the bad boys will take it off you. Additionally sections of the road heading into Jimani and the first section of road along the lake heading towards PAP are not suitable for a Scooter. If you were still that way inclined then a AG/Dirt Bike would make the trip and I am sure the bad boys would prefer a Dirt Bike over a scooter (they have their Reputation to think about).
So far we have been very lucky with the weather. If we have a few days of rain the living conditions of the displaced people in the tent cities will become intolerable (not tents but bed sheet shantys). If that occurs then there is a chance that the civil unrest will increase and then you will want to have some real support behind you in that situation.
My advice would be to Donate money to the Red Cross. Then apply for a job or volunterr position with an NGO and come across under their logistics and protection. Haiti can use your skills and experience however not as an unsupported individual on the ground at this stage (possibly in 3 months). By way of example - my vehicles have returned 3 well meaning volunteers back to SD over the last 4 days. They left due to the lack of clean drinking water and they had developed diarrea. One of them had his backpack stolen because he was not able to secure it during the day whilst he was working on "clearing debris".
Anyway no one is knocking you for wanting to help and if you do get over here then take care and be safe.