Help fixing skimmer

[Hawkdl2]

I got this double HOB skimmer that I don't know much about. I'm guessing it's an older CPR BaKPaK, but I'm not sure. In any case, it did not come with the powerheads so I bought a couple of Maxijets. However, I cannot figure out how to connect them to the intakes. Does anyone have a skimmer like this or know how to do this?

Also, are there supposed to be rubber rings around the collection cups for adjustment, or can I mod it to use a thumbscrew?