According to the documentation it is not possible,the workpackage consisting of 4 items usually (General,Attachments if enabled,attributes if enabled,comments if enabled,forms if enabled,any other custom stuff if enabled) can be only accessed once the workid ,subworkid is known. When you start the workflow from lapi you will be given the workid,subworkid so theroretically you can get the workpackage after start and look for the comments package and update it.
You can also create your own api if you know oscript and there is a tutorial in the communities web site that shows how to write ones own api ,if the provided methods don't suffice.
I would also ask you to take a look at enterprise web services methods to see if you have any better implemntation there.
I will aso check thru builder if methods are available,but undocumented later.
Well, if I called the wrong number, why did you answer the phone?
James Thurber, New Yorker cartoon caption, June 5, 1937
Certified OT Developer,Livelink ECM Champion 2008