{exp:safecracker channel="portfolio" return="/admin/ENTRY_ID" entry_id="{segment_2}" preserve_checkboxes="yes" safecracker_head="yes"}
{!-- Matrix field with upload cell --}
{field:your_matrix_field_name}
<input type="submit" name="submit" value="Submit" />
{/exp:safecracker}
If you don’t want to show the entire matrix field… then it gets really complicated. Basically… each field type handles itself in the SAEF. So if you’re trying to just display one field in the matrix, you’ll find it rather difficult.