If all these 1's need to be contiguous, connect an octal tri-stateable buffer (hc240 or 241, with appropriate input levels) to the I/O pins on one of the hc299's, then simultaneously:
1. Enable the buffer,
2. Disable only the outputs of the chosen hc299 (high impedance state),
3. Put the chosen hc299 in load mode,
4. Clear the remaining hc299's.
5. After 1 or more clock cycles, simultaneously disable the buffer, enable the chosen hc299, remove the clear on the others, and return to shift right mode.
This will take one control signal, and probably its complement, and it needs to be clock-synchronous.