Assuming there are no actuals, ie no progress, to start with.
This is where the task usage view becomes so handy.
The easiest way is to break the task into two separate tasks, stage 1 and stage 2, where stage 1 is the FS0 predecessor, and each with whatever duration will match the dates you have in mind, and then assign the resource to stage 1 at 100% and to stage 2
at 50%.
For your dates, I make the two durations 66 days and 43 days, so total 109 days.
Then you can make a new task (named "both stages") with duration 109 days and assign the resource at default 100%. Then use the task usage view, with the timescale set to days on the bottom tier, and set the task type fixed duration (task information,
advanced), and copy the work over 43 days in stage 2 and paste into the work for the corresponding date range for "both stages".
Another (easier) way is to make a single task, 109 days, assign the resource at 100%, set the task type to fixed duration, and then use the task usage view to input 4 hours of work at the first day of the 43 days. Then, select the work for that day and all
of the remaining 42 days and with the fill button on the ribbon, or ctrl_R, fill the 4 hours to all of the other days.
Alternatively, the hard way to do it is just make one task of 109 days, assign the resource at 100%, set the task type to fixed duration, and then use the task usage view and type in 4 hours of work into each day of the 43 days, but that's the hard way.
