create a session using proxy

I cannot find in the SessionOptions a way to setup proxy address and port, am I missing something?
if not, is there any idea to add this feature to the .net lib?
if not, is there any workaround?
thanks.

See SessionOptions.AddRawSettings:
https://winscp.net/eng/docs/library_sessionoptions_addrawsettings
https://winscp.net/eng/docs/rawsettings