Yes it's possible to do that.If you want to send the main tileset to your new ROM first open block editor,pictures tab,and then click Save tileset 1,after doing that you have to save all the palletes.so you need to save all the palletes that the tileset 1 is using,so on block editor click the "palletes" tab,then click "write current pallete to file" Do this for all the palletes you have edited/the tileset is using.After doing that go to your new ROM and open up block editor,pictures tab,load tileset 1 and load the tileset you saved earlier.It will load up but the tiles will look messed up,so then you have to load your palletes by clicking the "palletes" tab and click "load current pallete from file". And that's basically it,It's a bit tough to explain but it's pretty simple to do,if you have any problems with it just tell me.