I changed out the oil in the air shocks on my '03 Ultra. Used the "invert and let drain" method to get out some of the oil followed with the use of a mityvac (see pix below) to get the rest of the oil out (still inverted). I did get a hose barb fitting that threaded into the port on the shocks to make it easier to get a good seal on the mityvac's hose.
Key is to collect and measure all the oil coming out of each shock. Should be around 11 oz. (The lower profile shocks may be around 10 oz.).
On refill, just right the shocks and fill the cup with clean oil. If you can find a larger cup that will fit the mityvac that might make it possible to refill in one step. I had to refill the cup a few times.
Some guys are using 10 wt or higher to get a firmer ride with not as much air pressure required on the shocks. I think HD Type E is a 5 wt oil. Not sure what their other "racing" wts are.
Another method is to put the shocks back on the bike one at a time and used the weight of the bike to help "cycle" the shocks. With a longer bit of hose and a funnel, compress, pour in some oil, then extend the shocks so that all the oil gets in the shock. Have to repeat the process a few times.
There may be some easier ways to refill the shocks especially if you have a press handy. I didn't. But here is a neat DIY I saw on another Harley forum:
Changing oil in your air shocks
Cheers,
TQ