You should be able to force updates during your windows update timeframe.
First in the computer catalog area, create one or more groups for your lab computers. (Remember computers may be in only one group here, so you may need to get creative depending on your needs). Optionally, you can create a dynamic group if the target computers all conform to a particular addressing or naming scheme.
Next, in the Client side tasks area, under updating tasks, create a new task for your lab computers
Task type will be update program or VPS. Give the task a name that reflects this is particularly for labs
In the iAVS area select to update either definitions or program definitions.
As this task woud run during your maintenance window, I would select the don't reboot if required option - allowing you to force a reboot at the end of your window in order to process your other software updates.
in the Computers area of the task, instead of the default "*" (everything), use the browse option to select only the lab computer groups created above.
You may need to adjust the processing options if you have a large number of computers to update in a short time, but it is likely the defaults should be reasonable. If you have a few machines missing updates on a regular basis, you may consider increasing the number of threads or decreasing the push lag.
Finally, in the scheduling area, add one or more scheduler tasks to actually do the update at your desired time. depending on your desired update frequency. You mentioned a weekly maintenance window, but for virus/network protection, I would seriously consider a nightly one. (I would also name these Schedules indicating frequency)
Hopefully this should point you in the right direction.
Regards
