For PowerCenter the answer is: you may be able to find out what connection type is defined for each source / target / lookup (via the view REP_SESSION_CNXS), but you cannot find out for sure whether these connections have indeed been used when the sessions ran. The point is that defined connections are one thing but that connections can also be set as session parameters via a parameter file; and the fact which real connection a session parameter was used for any particular mapping execution can only be found in the workflow / session log files, nowhere else.
About IDQ I cannot tell, I don't know whether session connections (do they exist in IDQ?) can be parameterised.
No matter whether this works or not, if there's no Metadata Exchange view for IDQ which shows the connection, you can still export all affected IDQ workflows to XML files and parse these files. Please don't ask me what to parse for, no idea.