What sort of modifications.. grinding out holes/grinding off threads? And to what extent.. a little, a lot? I'm going to look at it today (was waiting for it to arrive on a truck).
As best I can remember after looking at my Jacks:
On the extra long Omega jack I'm pretty sure that I cut the pin or bolt off the crossbeam with a hacksaw, drilled it out and tapped the hole. I then attached the crossbeam to the saddle of the jack with a bolt from underneath and into the (now) threaded hole in the crossbeam.
On the smaller jack I drilled a hole in the saddle to accept the pin in the center of the crossbeam. I don't think the pin that's in my crossbeam now is what came in it. I think it came with a bolt that, again, I cut off, threaded with a tap and and inserted a bolt with the head cut off which became the pin that's now in it. I don't have a grinder or I could have just ground the bolt down.
On my smaller jack the crossbeam now just lifts off the saddle so I can use the jack for other purposes. On the larger Omega jack the crossbeam is bolted on so can be removed but it takes more time.
How you'll need to modify, if at all, depends on what type of jack you have and what sort of pin or bolt the crossbeam has. All of my modifications were made with simple hand tools - drill, file, tap, wrench, etc.
Hope this is of some help to you.