You don't have to do anything. You can use alkaline,NiCad, or NiMH battery cells without any ill-effects.
For the 45CT series, NiCad or NiMH may batteries may result in the strobe is a bit weaker (someone tested it to be about 1 stop).
But for the 45CL series, there is no difference in the strength of the strobe.
Metz just over-engineers.
I currently have CT-1 (2 copies), CT-4, CL-1, CL-4, and Hasselblad ProFlash 4504 (CL-4 clone, I think). I've been using nothing but Sanyo Eneloops and Quantum Turbo.
I did open up 2 copies of the CT-1 and did the modification of moving the ground connection, but then I found out that it made little difference, if any.
I put some cheap 1.5v alkaline batteries to test the flash, oops, nothing happened. I suspect something catastrophic. I removed the batteries and tried with eneloops and still the same.
I was very disappointed at this moment and tried to contact the seller.
Nevertheless, I want to try for one more time and I put back 1.5v and turned it ON...la la...everything worked. I suspect some contact problems with battery basket....
Does anybody have such a behaviour with this flash?
You need to ensure the polarity of the batteries when you insert them in the basket is correct because the + and - on old battery baskets are often worn off look at the instructions for the 45 CL4 on the Metz website.