Rel subwoofer high level connections with McIntosh integrated amp

Connect it to the same taps (4 0hm or 8 ohm) that you use for your speakers.  
If you are using bananas for your speakers then used spades for the rel leads and vice versa.

The rel isnt sucking any power from your amp just the signal...  

yes

straightforward - just use same taps

Doesn't matter which taps are used. No reason to add another connection to the ones used for speakers. Doesn't matter, because all these high level input circuits use a resistor, typically 20k Ohms to 50k Ohms. That is why it doesn't "suck any power". Its also why it doesn't matter which taps you use.