There's probably some other way I'm not aware of. If it's a terrain, go to File -> Export and save it in the .obj file type. If it's B6 or greater you're using, you can export boolean'd objects. I think there's a pattern to follow (or at least this is what I always do) go ahead and click the "C" button in that object group. Bryce will take some time to "combine" the two boolean'd objects. Then go to File -> Export and save that new object in .obj.

If there are mats involved, it may take Bryce a bit of time exporting them all too. For the Ivy Generator (IG), I just export with a grey mat which makes exporting quick.

Maybe there's some other way to export... I haven't been experimenting with this feature too closely. I've made some arches and pillars and exporting to IG this way.