Hello,  Unfortunately the ScaleIO Gateway cannot be used to install packages via REST API. The installation manager uses SSH to install the packages, once the packages are installed, you can then use REST API to configure and query the ScaleIO cluster.  Hope that helps.
We would like to install these packages programatically and avoid SSH. Can we use SVM Installation manager using a REST API? If so, how would you go about doing this? 
REST API for installing LIA, SDS packages to support Vmware Direct Path I/O