There is some probability that you will damage the frame by doing this. There are ways of estimating how probable it would be and how long it would last, but you really won't know for sure until you do it. It'll depend on the type and size of tubing, length of stays, etc.

So just take a bare 130mm hub or someone else's 130mm wheel and put it in there and get a feel for how much effort it would take to spread them. If you can get it in just with finger strength it'll probably be OK; that is, it'll be a long time before something cracks. What the hell, you know you want a new frame anyway.