Jake,
I find the best way to make guy friends out alone (assuming you want a wingman to pimp it with) is to go talk to girls with those guys and earn their respect by doing some approaches they probably wouldn't do themselves and then introducing them to girls they wouldn't have met otherwise. Make sure you get them talking to hot girls (assuming they have an inkling of game) and keep the group energy going. Be prepared to do most of the leading ("hey lets all go sit down over and grab a table", "hey lets go grab a nightcap at Jimbo's place") so make sure you keep tabs on what everyone's dynamic is (i.e. if your new friend Chad is the weak link and you can tell his girl is losing interest involve the girl in the conversation and improve her mood).
Basically you make their night ten times better by having met you since now their meeting more hot girls than they would've without you, if your bringing the energy there having more fun than they would've without you, and if your ballsy your now this crazy ballsy guy that gets girls and just says whatever to the hottest girls in the club and pulls it off. That's what I go for at least.
Then at the end of the night if you've really had some cool experiences with said new friends, even if you don't all pull girls for sex, you just say "guys this has been a sweet night we need to do it again tomorrow or (X day). You guys ever been to xyz place on Mondays? Dude the hottest girls of the city and the best music, you gotta check it out. Give me your phone # and we'll go pimp it at the (X awesome club) on Monday."
Bring them value and they'll be much more likely to hang out again. Value for guys is hot women, positive fun energy, and status (no one wants a lower status friend).
Your goal is to try to get them laid and have them see you do some ballsy gangster pimpin'. Depending on how much game and status these guys have will depend on how "WOW"'ed they'll be by you. If there less good with women and not ultra high status then you'll be coming in above their level (which is easier to make friends with in my experience). If they're good with women and higher status then you'll be matching their level much more and at that point the value your bringing is more a matter of "do I click with this guy and have good chemistry and a wingman or not" (which is really the ideal situation in making friends).
Last note is another good way to make guy friends is to find out what their interested in and if you guys click propose that you go do xyz other cool activity together soon (i.e. if you both surf then go surf when the surf is up). Seeing each other doing different activities will yield more investment and now you aren't pidgeonholed into the "this is my friend I go to bars with" but are more or less have a foundation to be actual friends.
-Rob