Keg carbing question.

[Oh Crap]

Please be gentle it's my first time....honestly I'm a virgin 
Used to own a pub so have most of the gear for kegs.. I have 2 beers ready to keg/bottle this week, a cream stout and a blonde ale.  I planned on using 2 20L kegs.  My problem is that the reg I have is for mixed gas, I have the gas but am fairly sure it is useless for force carbing.  I was thinking about naturally carbing with sugar etc. then hooking up to gas and leaving it for 2/3/4 wks and serve through a Guinness style tap.  Will this work?  And do I use the same amount of sugar or less?
Cheers for any advice.

[molc]

Think it's half the normal priming ammount for natural carving, but as you drain the keg, the co2 in the beer gets released. I think you'll still need to keep a gas line connected to keep the carb level constant.
Only got this from reading online though, so some of the other lads might correct me.

[Hop Bomb]

Yeah you can just prime your beer in the kegs with sugar to carb it. Then just use the gas to dispense. There wouldnt be any need to leave the gas on for 2/3/4 weeks. Id actually advise against that as you could over carb your beer & if you have a leak you'll lose the whole tank of gas. Prime your kegs with sugar to your desired level of carbonation (Leave them somewhere warm for a week or two).

http://www.brewersfriend.com/beer-priming-calculator/

[Oh Crap]

Calc is very handy but considering it is going on mixed gas, 70/30, do I use the same amount of sugar as per bottle conditioning?

[auralabuse]

You can use the mixed gas to carbonate,  will take longer but it works.  I used 50/50 gas,  carbed for about 2 days and it turned out fantastic