now, in english:
A switch by default does not have any "interfaces" of its own. So, you create the interface "vlan 69" (which is basicly a physical interface directly hard-wired into vlan 69).
Then, just create a dhcp pool that will be handed out by that interface and make the ports part of that vlan.
You can skip the vlan re-assignment by using int vlan 1 instead ov vlan 69.