This works for the RF installation DVD so it will probably work for the MegaPack too. Take the DVD to a computer that has a DVD and copy the entire contents of the DVD to a USB Thumb Drive. Then give the Thumb Drive the same Volume Label that the DVD has. Then you should be able to install the MegaPack from the USB Thumb Drive. Of course you'll need the Serial Number to install them.
I would expect the process technoid described to work. Alternatively you could create an .ISO from it, then transfer that to the computer where you want to install and mount it there. Just a couple slightly different ways of achieving the same result.
Note that basically everything contained in the Heli Mega Pack is now part of RealFlight Evolution, no extra purchase or installation required!