Sure. Where are you having the most issues? Need lots more info. Running Windows (which version?)? Any errors in Task Scheduler?

It's only about 5 minutes of work. No "learning" necessary since others have already created the Scheduled Task for you. There's no programming involved.

I modified NixChix's original scheduled task with the following changes:
1. Changed path to 64-bit BOINC.
2. Changed the triggers to run for 24 hours instead of 12.
3. Added a trigger for :17/:47 after the hour.
4. Changed the task to run under SYSTEM. I agree this isn't as secure as running the task under a local standard account or a limited BOINC account, but it was a quick-and-dirty way for me to accomplish it.

Instructions

1. Copy and paste the following into your favorite plaintext editor. You can even use Notepad if that's all you have. Save it as "BOINC.xml" or any file name you prefer. Just make sure the extension is XML.

<?xml version="1.0" encoding="UTF-16"?>
<Task version="1.4" xmlns="http://schemas.microsoft.com/windows/2004/02/mit/task">
  <RegistrationInfo>
    <Date>2016-12-14T00:09:54.4534673</Date>
    <Author>NixChix</Author>
    <Description>Run boinccmd to cause an update to WCG</Description>
    <URI>\BOINC</URI>
  </RegistrationInfo>
  <Triggers>
    <CalendarTrigger>
      <Repetition>
        <Interval>PT30M</Interval>
        <Duration>P1D</Duration>
        <StopAtDurationEnd>false</StopAtDurationEnd>
      </Repetition>
      <StartBoundary>2018-03-26T20:03:00-04:00</StartBoundary>
      <ExecutionTimeLimit>PT30M</ExecutionTimeLimit>
      <Enabled>true</Enabled>
      <ScheduleByDay>
        <DaysInterval>1</DaysInterval>
      </ScheduleByDay>
    </CalendarTrigger>
    <CalendarTrigger>
      <Repetition>
        <Interval>PT30M</Interval>
        <Duration>P1D</Duration>
        <StopAtDurationEnd>false</StopAtDurationEnd>
      </Repetition>
      <StartBoundary>2018-03-26T20:17:00-04:00</StartBoundary>
      <Enabled>true</Enabled>
      <ScheduleByDay>
        <DaysInterval>1</DaysInterval>
      </ScheduleByDay>
    </CalendarTrigger>
  </Triggers>
  <Principals>
    <Principal id="Author">
      <UserId>S-1-5-18</UserId>
      <RunLevel>LeastPrivilege</RunLevel>
    </Principal>
  </Principals>
  <Settings>
    <MultipleInstancesPolicy>IgnoreNew</MultipleInstancesPolicy>
    <DisallowStartIfOnBatteries>true</DisallowStartIfOnBatteries>
    <StopIfGoingOnBatteries>true</StopIfGoingOnBatteries>
    <AllowHardTerminate>true</AllowHardTerminate>
    <StartWhenAvailable>false</StartWhenAvailable>
    <RunOnlyIfNetworkAvailable>true</RunOnlyIfNetworkAvailable>
    <IdleSettings>
      <StopOnIdleEnd>true</StopOnIdleEnd>
      <RestartOnIdle>false</RestartOnIdle>
    </IdleSettings>
    <AllowStartOnDemand>true</AllowStartOnDemand>
    <Enabled>true</Enabled>
    <Hidden>false</Hidden>
    <RunOnlyIfIdle>false</RunOnlyIfIdle>
    <DisallowStartOnRemoteAppSession>false</DisallowStartOnRemoteAppSession>
    <UseUnifiedSchedulingEngine>true</UseUnifiedSchedulingEngine>
    <WakeToRun>false</WakeToRun>
    <ExecutionTimeLimit>PT1H</ExecutionTimeLimit>
    <Priority>7</Priority>
  </Settings>
  <Actions Context="Author">
    <Exec>
      <Command>"C:\Program Files\BOINC\boinccmd.exe"</Command>
      <Arguments>--project http://www.worldcommunitygrid.org update</Arguments>
    </Exec>
  </Actions>
</Task>

2. Open Task Scheduler as Administrator. (Right-click, then click on "Run as administrator.")

3. On the left side where it says "Task Scheduler Library," right-click and select "Import Task..."

4. Choose the XML file you just saved.

And you're done! Be sure that Help Stop TB is the only project selected in your "My Projects" page on World Community Grid. Of course, once you've reached your HSTB goals, this task should be Disabled or deleted.

When I changed the update times, I started getting work units again.

29-Jan-2018 10:03:20 Started download of 013880a38015fe509440abda7f3aa0cb.tpr
29-Jan-2018 10:33:18 Started download of 39f43f6274f625d7355fd78f95a5faed.tpr
29-Jan-2018 16:03:21 Started download of 24c82dbb69eeb2af00d52dc34178a478.tpr
29-Jan-2018 16:03:21 Started download of e2ac68f1107f2fda717a5a6ef1558385.tpr

27-Mar-2018 16:17:24 Started download of e1bb74b0e45b81dfa4692877a1075c61.tpr
27-Mar-2018 16:17:24 Started download of fd3d5b3f8f1bfe9e0b33a06320bea806.tpr
27-Mar-2018 16:19:31 Started download of fd1536332cafc58f78b6f0ecb4eeae90.tpr

I didn't even bother making a Shell script in Linux. Just put the command directly in crontab:

03 *    * * *   boinc   boinccmd --project http://www.worldcommunitygrid.org update
17 *    * * *   boinc   boinccmd --project http://www.worldcommunitygrid.org update
33 *    * * *   boinc   boinccmd --project http://www.worldcommunitygrid.org update
47 *    * * *   boinc   boinccmd --project http://www.worldcommunitygrid.org update

@adriverhoef, thanks for the advice. I'm a 'nix newbie, so I didn't know much about how cron works and just set it up within a few minutes. The BOINC client package automatically created a "boinc" limited user and runs everything under boinc, so I figured setting up the crontab to also run as the "boinc" user would limit the execution privileges of the command.

I guess I haven't learned the security difference between running the system crontab as "boinc" user vs. running a personal crontab as "boinc." Maybe there is a difference after all, even though they both would run as "boinc."