Reviving a really old thread here. I am considering using the rubber cement, just wondering if it works similarly to the vulcanizing fluid in terms of method. When I use the vulcanizing fluid, the steps are
sand tire to make rough and clean
apply fluid sparingly, but in an area bigger than the patch
allow to dry
press patch on without moving - instant bond formed here
press firmly, rolling the tube/patch between my fingers for 10-15 seconds
let sit over night
good to go.

I presently have a stock of rather large patches (25mm) which I am using on 25mm tubes. So the patches don't just plot down on the tube, you need to bend and roll them to get full contact area. I have had no real problems with the patches, but i am running low on fluid and exploring my replacement options.