i didn't have much of any problem when i tried.
A) what are you starting with? 2 Rejuv's 3 pots works for skarner (works for a lot of champs, even AD ones). Turn one rejuv into phil stone, the other into emblem (for aegis) or locket (viable on any tanky jungler, pretty much... AD junglers turn em into Tiamat)
B) if you can't do red pre-3, do wolves>blue>wraiths>wolves. It'll get you to level 3 (this helps a bunch for most any champ, if they normally cut it close going straight to red, it's just a minor speed cut). That'll make Red easier
C) Do you take his E? People call Skarner's E worthless, but it's really not half bad for one point in the early jungle. It's generally 50ish hp per use. 1/3 of a health pot every few seconds isn't bad
Also, screw armor reds. Go with AD or something. It'll boost your Q damage and AA damage. Armor reds are less efficient and frankly unnecessary for just about any jungler.
*edit* people are saying AS red runes as well, those would be fine too. But they aren't necessary, I've done it just fine with AD.