Yes! You can do collaborations at both the album level and the track level with Boost Collective. 

Album Level Collaboration

Note that if you are uploading a single, you must add your collaborators at the album level, and not at the track level. Additionally, note that collaborations at the album level take up an artist slot, even if one of the artists is already being used on your account. 

To do this, simply add the collaborators in the upload form here as seen below:

Track Level Collaboration

To edit/add the collaborators for each specific song within a single Album/EP release, find the release in your 'Releases' section, click on 'Edit Tracks', and then click 'Edit' again for the specific song you want to add collaborators to. Here's a visual: