this may sound noobish but how do i gain write access to /system/app/ ? I can't get astro or expert file manager to write to the folder.
It's probably easiest to modify the image before you try to load it onto your tablet. If you run Linux on your desktop you just need to run the following commands:
sudo mount froyo.img /mnt -o loop
cp gapps/* /mnt/system/app/
sudo umount /mnt
I'm assuming you've named the image file froyo.img of course. You should be able to modify the image fairly easily in Windows using 7zip.