I'm currently logged on to SOLAR to register as an exchange student, but it is saying I have none of the prerequisites necessary.
However, I do, just from my home University.
Mc McMaster advisor was supposed to acknowledge this and apply a waiver in time for registration, but it doesnt look like she did.
No I cant register for any of my courses, and my time is almost up!
Is there anything I can do, or anyone I can contact ASAP!?

Call the Office of the Registrar first thing in the morning (9 AM Eastern time). They will help you. They will also help you get seat authorizations for mandatory courses, as well as (possibly) some electives, if you can indicate their necessity for your chosen path.

Thanks for your reply, thankfully this situation is almost resolved now!
Waivers have been applied, and 3 out of 5 required spaces have been saved on my desired courses .. I'm just waiting on the other 2 as they are from another faculty!
Just wondering, can you register multiple times during the 7 day log on period on SOLAS?
If so, I'd like to register for 3 of my classes now and the rest when I can, so I can get my email activated, sign my payment agreement, etc ..

Yes you can! I logged on to double check mine this morning because I was so exhausted last night by the time I got in.