The that came-up to me the /MO
switch:
SCHTASKS /Create /SC weekly /D FRI /MO 2 /TN THE_TASK_TM /ST 10:00 /TR c:\some.bat
with it and /sc weekly
you can point the number of the weeks you want.
may be there's an easier way but I need to think a little bit.
Edit - I was wrong./MO it the interval so you can leave it to 2 - https://technet.microsoft.com/en-us/library/cc725744.aspx
search for "every other week" to hit the correct example.
Other ways are to use the scheduled tasks UI in the control panel or to pass an XML to the schtasks similar to this (edit the things you need) :
<?xml version="1.0" encoding="UTF-16"?>
<Task version="1.2" xmlns="http://schemas.microsoft.com/windows/2004/02/mit/task">
<RegistrationInfo>
<Date>2015-04-24T18:41:41.2112185</Date>
<Author>computer\user</Author>
</RegistrationInfo>
<Triggers>
<CalendarTrigger>
<StartBoundary>2015-04-24T18:40:56.2090861</StartBoundary>
<Enabled>true</Enabled>
<ScheduleByWeek>
<DaysOfWeek>
<Friday/>
</DaysOfWeek>
<WeeksInterval>2</WeeksInterval>
</ScheduleByWeek>
</CalendarTrigger>
</Triggers>
<Principals>
<Principal id="Author">
<UserId>computer\user</UserId>
<LogonType>InteractiveToken</LogonType>
<RunLevel>LeastPrivilege</RunLevel>
</Principal>
</Principals>
<Settings>
<MultipleInstancesPolicy>IgnoreNew</MultipleInstancesPolicy>
<DisallowStartIfOnBatteries>true</DisallowStartIfOnBatteries>
<StopIfGoingOnBatteries>true</StopIfGoingOnBatteries>
<AllowHardTerminate>true</AllowHardTerminate>
<StartWhenAvailable>false</StartWhenAvailable>
<RunOnlyIfNetworkAvailable>false</RunOnlyIfNetworkAvailable>
<IdleSettings>
<Duration>PT10M</Duration>
<WaitTimeout>PT1H</WaitTimeout>
<StopOnIdleEnd>true</StopOnIdleEnd>
<RestartOnIdle>false</RestartOnIdle>
</IdleSettings>
<AllowStartOnDemand>true</AllowStartOnDemand>
<Enabled>true</Enabled>
<Hidden>false</Hidden>
<RunOnlyIfIdle>false</RunOnlyIfIdle>
<WakeToRun>false</WakeToRun>
<ExecutionTimeLimit>P3D</ExecutionTimeLimit>
<Priority>7</Priority>
</Settings>
<Actions Context="Author">
<Exec>
<Command>the_bat.bat</Command>
<Arguments>x</Arguments>
<WorkingDirectory>c:\</WorkingDirectory>
</Exec>
</Actions>
</Task>