FOLLOWING THE SUCCESSFUL DISCOVERY OF A 1.2 D PERIOD FROM HIGH-CADENCE SWIFT/XRT MONITORING OF THE ULTRALUMINOUS X-RAY SOURCE (ULX) IN NGC 55 WE PROPOSE SIMILAR MONITORING OBSERVATIONS (0.5KS AND 1.5KS?5 VISITS PER DAY FOR 10 DAYS) OF TWO MORE VARIABLE ULXS WITH KNOWN OPTICAL COUNTERPARTS (HOLMBERG II X-1 AND NGC 247 ULX). OUR MAIN GOAL IS TO SEARCH FOR ORBITAL PERIODS IN THE RANGE OF A FEW 10S OF HOURS IN THESE TWO SOURCES. THIS PARTICULAR PERIOD RANGE TYPICAL OF STELLAR-MASS BLACK HOLE BINARIES HAS NOT BEEN PROBED BEFORE FOR ULXS. ANY DETECTED PERIODS WILL BE AN IMPORTANT STEP TOWARDS DYNAMICAL MASS MEASUREMENT OF THESE COMPACT OBJECTS. WITH NGC 55 ULX WE HAVE ALREADY DEMONSTRATED THAT SWIFT WITH ITS EXCELLENT X-RAY SENSITIVITY AND FAST MANEUVERING CAPABILITY CAN DEFINITELY CARRY OUT THESE OBSERVATIONS.