OSX 10.5.8 and Summa cutter/plotter

arrrgh this is getting complicated

i've got a mac running 10.5.8 with the latest version of Flexisign (8.5)

to print/plot flexi drawings a vinyl cutter is used (Summa T750 Pro)

Right now sending plots are very sporadic at best... not consistent
support from summa says the drivers i need are on the cd that came with the plotter...

flexi has a control driver for the summa plotter built in
summa says i also need a communication driver as well

minor detail, the drivers on the summa cd are designed for Mac OS Classic and wont run on 10.5.8

checked the webs for new drivers, none to be found

i read about sheepshaver which is a mac os classic emulator but i need a classic driver to work, not a classic program...

i have found MacSign Cut which should have the communication drivers i need, but i want to research other options before buying more software...

Goal- to be able to send plots to summa T750 plotters from flexisign without having to unplug/plug in the usb cable when the plots dont go

any suggestions on a fix??