Custom viewport

Can I make a sort of custom viewport? I'm trying to split my screen evenly, 3/4 showing a tilemap on the left and 1/4 showing a text panel on the right. I'm using a scroll-to sprite to allow me to scroll around the tilemap but I can't get the math right, other than trial and error, to keep the tilemap centred in the left 'viewport'. I want, for example, to hit a key and have the scroll-to go to various corners of the tilemap, or just allow it to scroll around with the 8-way behaviour. But it should always keep the tilemap centred on the left 3/4 of the screen rather than centrally.

So basically, I want to create a 'window' on the left and a text-panel on the right.

Yes, you can make a "clipping mask" type layer by using the "force own texture" property on a layer along with an object with blending modes to specify the area you want transparent or otherwise.