The board appears to have a QSPI flash for configuration. IIRC, iMpact did have a way to program arbitrary data -- normally an OS -- as well as the normal .bit file. The tools program the FPGA with a minimal build that has the jtag to config-pins interface. You would still need to read the image from flash and write to RAM.
--edit: it looks like the board manufacturer's programming tool also allows you to write data files to the flash in addition to the normal programming file.