i'm looking for a macro to set temp HP

i have a lot of players who like fiendish vigor, and i want to make a macro that then can put on there sheet so when they roll the temp hp, it automatically applied to the @{hp_temp} on there sheets, but i can't think of a way to set it. i'd prefer it without APIs but if not i'd still like to know. something that would be along the lines of "set @{hp_temp} [[1d4+4]]"

This is only possible with API scripts. 

what would be the API script to use and what would the macro be? if you don't mind me asking i'm assuming Tokenmod but from there i'm stumpt

ChatSetAttr will do what you need, available via one-click library. Something like this might work: &{template:default} {{name=Fiendish Vigor}} !setattr --silent --sel --hp_temp|{{[[1d4+4]]=Temp HP to @{selected|token_name}!}}!!! This is pretty basic and would overwrite whatever value of temp HP they have. It might be an idea to have it check if the current value is already higher, and not apply the HP if that's the case. Or you might not be worried about it.

Looking at ChatSetAttr I wouldn't know how to do the first thing with it, thank you for the code. I will try and mess around but I doubt I'll manage lol