Hot Bar Manual Solder
This pdf has a description of hot bar soldering if you're unfamiliar with it. (It is the top Google result, but it's a popular intro.)

25 mil pitch on a connector isn't too bad; it's the characteristics of the flex cable that will bite you.  If I misinterpreted, and you have the hot bar connector on the PCB they're sending you, then you shouldn't have too much trouble.

If, however, you're soldering off of the flex cable that attaches to the hot bar connector, you left out whether your flex cable has windowed, cantilevered, or unexposed leads.  If you have a choice, cantilevered will give you your best chance of success because the leads will be thicker, and you won't damage the backing.

With any of the options, soldering leads onto the 25mm pitch should be alright.  Use 28 gauge wire or finer. I did a 20mil pitch, 10 mil trace cable a few weeks ago, and that went OK.  (I did have the use of a stereo microscope, you'll want a good magnifier at the very least.)  I damaged one practice cable beyond repair - The backing burns like the insulation of a wire, and, and the traces are not copper leads, they're copper foil.  Some form of strain relief will be absolutely mandatory to keep your wires from breaking off. 

However, I would advise that it will be easier if you can solder directly to the connector leads instead.  It's easy to damage the very thin traces on your flex cable, but the connector will be much sturdier. 

Whatever you end up doing, make sure your wires are as short (and equal length) as possible, you might be dealing with some very high speed stuff! A 500MHz signal (for VGA resolution, using 2-wire differential signals) has a wavelength of just 5cm!