A few times I've been out walking or backpacking and have no moleskin with me. Sure enough, my boots start giving me blisters. How can I prevent or treat hotspots and blisters without using moleskin?
The key is reducing friction. Duct tape can be a good preventative as long as you get it on before a blister forms. After the blister is there, it's harder to recommend as once you're ready to remove the duct tape, you might pull the blister along with it.
Other options are to make sure you're wearing dry non-cotton socks. If you find your feet sweat a lot while walking, make sure you have good moisture wicking socks or you change your socks as the moisture builds up. Rotating socks gives one pair a chance to dry out while wearing the other.
If you're in the middle of a hike and forming hotspots without any tape, extra socks or moleskin to help, you may have to just slow down. Take a break, take your boots and socks off and give everything some time to dry out. It may be all you need to get back to civilization without developing full blisters.
I would imagine you might not have compeed, if you don't have moleskin with you, but I just thought I'd mention it as a nice measure to prevent/treat blisters.
I would also recommend carrying less weight and using a lighter pair of shoes, instead of a heavy pair of boots. Those blisters are your feet's way of telling you something isn't working well in there.
In such cases I try to tie my shoelaces differently, to change the way my foot sits in the shoe - if my ankle is too loose (thus the blisters), I would try to change that in case I cannot get any help. This is not a long term solution, especially if you tie your shoelaces too tight they may affect the blood circulation in your foot a bit.