[NTG-context] location of converted images

Dear list, images converted on-the-fly (m_k_i_v_*) are stored in the same folder as original images. Is there an option to change cache folder? Original files are stored in the read-only location. Script convert offers --outputpath option, but I would like to make the switch with script context, using mtxrun --script context <file>. Taco's talk 'mtxrun scripts' at the meeting http://meeting.contextgarden.net/2018/abstracts.shtml will hopefully show us even more magic. Thank you, Jano