Hi,
For example, I backed up the private keys of my addresses in the electrum wallet. How can I install multibit hd wallet from again using these private keys?
AFAIK, you can't import anything into Multibit HD and they don't adopt the same seed deviation method as Electrum. Hence, you need to send the coins to a wallet created by Multibit HD's seed.
You can import into Multibit Classic though[1]. Can go through more in depth for you, if you need.
[1]
https://multibit.org/help/v0.5/help_importingPrivateKeys.html