Put 2 M10 nuts on the threaded rod, (sometimes called stud iron), slightly further back from the length of thread you want to screw into the handle.
Lock the 2 nuts together using two 17mm spanners. Run the rod intp the handle as far as it will go by hand. Using one of the 17mm spanners turn the nut which is furthest away from the handle until either the rod is fully inserted or you have reached the desired length. Using the 2 spanners you then unlock the 2 nuts and run them off the rod by the opposite end.
If you want to lock the threaded rod into position in the handle you can remove one nut and use the remaining one to run down to the handle and lock it tight using the spanner. This will prevent the rod from coming loose and falling out.