Planner-list Project resource only on specific days

Hi,

I try to define my current project with Planner.
The project has different tasks, which have specific
lengths. But the resource (me) can only work on some
days of the week (Thuesday, Thursday, Friday) on the
project. What I need is a plan, whether or not I'm out
of the plan. The first task needs four days, but if I
start on 24th of October it must not be done on 27. 
of October (because I work on it on 25., 27., 28.
and 31. of October only). So the task ends in time 
on 31. of October.

How can I configure that without manually re-calculated
task times?

Thanks a lot
Andre