Hi Ryanm,
You can assign by two ways:-
a) Directly use the function is s-code like we use previously for plugins
eg.- s.eVar1=s_getLoadTime();
b) You can add the above code in your pageload time also.
This is for all other plugins also just create Plugin Initialization rule by Common Plugin Extension and then use there function in s-code or in rule without using the custom plugin,