Trying the ol' motorcycle bearing installation trick. Outside temps are around 0 degrees Fahrenheit. Should be cold enough to shrink headset cups and make and easy install of it.

& heating the frame head tube.. ?

Should work fine. BITD I used a deep freeze to shrink some hard-to-start piston pins when rebuilding my '74 Beetle. Handle with gloves so you don't warm them with your hands.

Worked like a charm! Cups pressed in with little effort. Will do it again on the next headset install.