How to season a carbon steel pan on an electric hob

To the question as asked: No, there are no more tricks. When you use the wrong tool for the job (in this case a too-small electric hob), then you can't expect the job to go well.

Nevertheless, there is an easy solution for you: Use the oven. If you are that worried about your rubber button, remove it before putting the pan in the oven, and pop it back in afterwards. But I use my own Mineral B in the oven frequently enough (and don't always bother to remove the button), and have had no problems with it.

I had never heard of the manufacturer's advise you cite, but if you absolutely want to stick to it (e.g. because of warranty issues) and are against the oven, you just have to live with a badly seasoned pan.

Options:

1. Move it around. I've often lived with kitchens that deprived me of gas in which I had to maintain woks etc on small/ highly centralised heat sources. I rolled the wok from side to side to heat the whole object, and kept wiping oil over the whole inner surface. Took time. You've got a flat pan, which should be easier. Just put it on max heat and move it steps around a circle, so you're effectively seasoning each small area sequentially rather than the whole thing at once.
2. Don't worry. That is, if your hob only heats a certain portion of the pan, then that's where sticking is most likely to take place, and hence that's the area whose seasoning you should be most concerned about. If you haven't got a perfect, shining black patina extending evenly right to the rim it won't affect the production of your crepes, which will be cooking on the bottom, mostly in the middle.
3. As rumtscho suggests, you could trying doing it in the oven. You could attempt this by either a) removing non-metal parts if there are screws or such allowing you to do so, and replacing them afterwards, or b) destroying unremovable non-metal parts (pare them off with a stout knife or a chisel, or whatever method seems appropriate) and then living without them, or binding on a comfily-shaped piece of wood if you've been left with only some kind of prong that doesn't feel very nice to grip. Yet another alternative is to use a towel/ cloth/ rag, as some chefs use all the time, which will also help you to keep everything clean as you go (doesn't almost everyone hate a slippery, oily pan-handle?), and reduce the risk of ever burning yourself.
4. Pop over to visit a friend who is the proud master of a more comprehensively-fitted kitchen and ask to borrow their gas hob for a smoky hour. If you're absolutely fascist about taking care of your pan thereafter (no slow-cooking of tomato-based or other acidic sauces, always dry it and heat it a wipe it with a few drops of oil when you've finished using it), once should be enough. Bring a bottle or some cookies, enjoy owing a favour, and look forward to further fun times in kitchens with said friend.