The enforced usage of "may" instead of "can" is old-fashioned and school-marmish. In all but the most stilted conversations, people ask for permission using can instead of may.
Can I get a little help here?
Can I borrow your car?
Can I take you to dinner Friday night?
All those are fine usages, and no one but a ninny would attempt to correct you for using any of them. On the other hand,
May I get a little help here?
May I borrow your car?
May I take you to dinner Friday night?
sounds more formal, with an extra dollop of politeness. One might even say that the dollop is not so much politeness as fussiness. Using "may" instead of "I" is fussy at best, hyper-corrective at worst. In my own case, I hardly ever use the construction except somewhat sarcastically, as in the following sort of situation:
Me: Do you have an extra pencil?
Co-worker: Yes.
[Pause while nothing happens.]
Me: Do you have it with you?
Co-worker: Yes.
[Further pause, while co-worker does nothing to produce a pencil]
Me: [Impatient at co-worker's coyness] May I borrow it, please?
In the above exchange I am using may instead of can because my co-worker is kidding around [she should have understood my initial question as a request to borrow a pencil, but is playing a little game] and I wish to speak to her as one might to a child.
It's unprofessional. There are quite a few websites which use this more casual, personal tone and sometimes it is much appreciated by the viewers. In other situations it could be viewed as immature and inappropriate. Know your audience and the tone you wish to present.
Best Answer
You can certainly use "likewise" anywhere it fits and there is no reason why you can't also use the word "also" in an academic paper. I personally tend to use "also" only when necessary but sure, you can do it.
also (adverb)
likewise (adverb)
They aren't exactly synonymous but they can often be used in the same places.