Thanks I think I understand that table now. I've just unromanized it for my reference (damn romaji).

Except I have heard people say いっきろ.

After searching Google it does seem that いちきろ is the more common way.
I say "more common way" because I have definitely heard いっきろ being used, even by Japanese friends.
Maybe いっきろ is just used in certain places?
I don't know, but either way いっきろ exists.

Edit:
A mail from my friend said:
さっき調べたら
いっきろは やっぱ方言で
いちきろってのが
全国共通なんだって:)

いっきろって
聞いたことない人もいるみたいだよー

Which explains why I have heard it, considering the friends I have in Japan all speak some kind of dialect.

This is what makes language learning fun.

And that fun is what keeps me learning Japanese ;)

Any counter that begins with an unvoiced stop would follow the pattern
いっ for 1
じゅっ for 10
ろっ for 6
はっ for 8

If the counter starts with an "h" follow the rule for 分

Else don't do anything special, e.g. 　枚　いちまい、にまい、さんまい、など

一軒＝いっけん
一点＝いってん
一丁＝いっちょう

These rules aren't rocket surgery. There are basically 2-3 patterns, and all counters follow these patterns. Hell, counters are more regular than English verbs. There are exceptions, but you learn them as you go, not by memorizing them all now.

Hell, I probably only know 10–20 counters, and very few of them get rotation in my daily speech. 軒点匹分角画頭本枚杯丁台次時日月年回羽冊組番曲体 are basically the only ones I know. I reverb to the good ol' Yamato counting otherwise: ひ、ふ、み、など.

Doesn't this mean that the counter doesn't follow the rules?

Let's say the rules apply to non-loan words.

http://www.trussel.com/jcount.htm has some information on whether to use ichi or hito.

The Counting Dictionary (jp) has a lot of information on exceptions.

Thanks for the links.

What are the rules for loan-words then?

That the rules don't apply to them. ;)