Hey bop,
First welcome to HSbaseballweb and hope you visit often. It's a great site with a lot of knowledge and perspectives about baseball.
Second you are going to find the retractable tunnel to be an awesome thing to have.
If it's not too late there is a kit you can buy almost anywhere online that has everything you will need to hang your tunnel.
Most kits will include
3 100' wire cables
6 hook and eye turnbuckles
6 eyebolts
70 snap links
Cost is around $200 or less
I had a 70 foot tunnel put into a barn that was close to 90 feet long. I bought a kit and it was more than enough to hang the one tunnel.
The cables are 1/8" thick.
It also wouldn't hurt about once a year to tighten the turnbuckles a little bit as the nets tend to cause the wire to stretch a little.
These are fairly easy to put together. I actually did all of mine by myself except for hanging the wire the net will hang from. I need two others to help pull the wire tight and then clamp it down.
I hope this helps but if you got any more questions please feel free to ask.