Back in about 2000, when internet commerce still sucked, local outlets just kept the more expensive and latest stuff, and I was particularly broke, I had to put a heatsink on a gold top CPU with no clips available. What I used then and which lasted for several years until decommissioned was using a "household cement" type glue. That stuff which is similar to rubber cement, and brands include UHU, Bostick etc. Not really found a great generic name for it where everyone knows what I'm talking about... Anyway, reason I picked that is I wanted some shrinkage when it set up. So I put the regular zinc oxide goop on the gold cap and "cement" all round the ceramic part and left it with weight piled on it overnight to "set up". So it worked, heatsink stayed on, but after a month or two the adhesive had turned an horrible brown color... but it held up, can't say if temps were great because it was socket 7, no thermistor, but didn't crash from heat that I know of. Then when I wanted the heatsink off again I scored the glue and twisted it off.... cleanup was horrible though, stuff made a mess, think I needed nail polish remover, but more than 10 years ago it had a decent amount of acetone.
Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.