Hi,
Yes you will need to install IRS 7.x.
As mentioned above there are some integration between IRS 7.x and HP SIM but you should not use them due to the fact that the IRS 7.x database can be corrupt.
In my personal opinion the move from Advanced IRS 5.x to IRS 7.x has complicated the solution. With Advnaced IRS 5.x we could see the CW column in HP SIM, we could also see the case number that HP has on the HW-alarm.
Now I need to have to application to keep a eye on, HP SIM and IRS 7.x.
Hope that all this will be solved in OneView.