I hire best vb6 programmer here, buget $500-$1000

[Schmidt]

1) he's making a requirement that the js be run through INet control - not sure I get why, but there it is.

Not sure what you mean exactly, but the example demonstrates, how to add your own (additional) js into the WB-Control -
and it should not be that difficult to re-route certain existing JS-functions over your own (newly added) snippets...

2) I'm not sure he's in possession or control of the js script, which means it's hosted remotely, will this still work in such case?

When we talk about DOM-interaction, then there isn't really any "remotely hosted" (as in "remotely run") JS.
What often sits remotely, are only the js-resources, and these are always downloaded into the DOM before a given Browser can execute them
(in the context of the Page in question).

And yes, your own added JS-snippets can run in conjunction with pre-existing (externally loaded) js-Resources in the context of a given external Page.

Olaf