Import photos from external disk into iCloud Photo Library via MacBook Air with not enough HD space I have 60 GB of photos on an external hard disk.
I also have a MacBook Air with an empty iPhoto app. The MacBook has 15 gigs left of HD space.

Can I import these photos directly into the iCloud Photo Library?

I can only find articles which explain how to upload your complete library to iCloud, after which it starts optimising for storage. However I don't have enough space to fit all  my photos on the internal hard disk.
First, you will have to update to Photos app on OS X, as iPhoto is not compatible with iCloud Photo Library.
Activate iCloud Photo Library and subscribe a storage plan that accommodates your pictures and anything else you have there (iOS Backups, for instance). Select the "Optimize Mac Storage" on the Photos app Preferences > iCloud pane. 

Then import batches of 10 GB or so of your pictures to the empty Photos app library; given you will have only 5 GB left I assume it will start optimizing right away. When you regain some space, you can add another batch.