Hi.
Opertation voltage of ePMP1000 is 12-30 VDC. The ePMP1000 power supply delivers 30VDC 500mA, where 7 and 8 contacts are + 30V, and contacts 4,5 are a return.
The UBNT power supply has an output voltage of 24VDC 1000mA. Contacts work the other way around: 7.8 - return, 4.5 is + 24V.
Theoretically, if you prepare a special cross patch, it should work. All actions are at your own risk. Most likely you will lose the warranty of Cambium.