[galaxy-dev] Is it possible to pass runtime values to workflows through the API?

Hi, I was wondering if is possible to pass runtime values to workflows thought the API? I want to run the same workflow for several inputs, but there are values other than the inputs that I need to change for each run. Is it possible to leave these values as 'To be set at runtime' and set them through the API? Also, I see 'Step Actions' do not support the option of 'To be set at runtime', could this be included in a future release, in other words, can this be a feature request? Thanks, Carlos