What are the rules for reading numbers before a foreign counter-word?

Is there a rule of thumb for knowing the reading of a number when it is written in western numerals, and is followed by a loaned counter-word?

For example, how would you pronounce the "1" in １セット? My first thought it to say 「いっセット」, but as far as I know it could just as easily be 「ひとセット」 or 「いちセット」. The Wikipedia article does not cover loan-word counters, and I cannot find anything on this topic.

Answer

I'm going to extrapolate the rules for Japanese counters onto foreign-counter-words.

Extracted from Nihongoresources:

---

Rules for 一

• 
  

  When followed by a counter starting with a syllable from the か—, さ— or た—column, いち becomes いっ

  
  


• 
  
  

  When followed by a counter starting with a は—column syllable, いち becomes いっ and the counter changes to a 'p' sound

  
  

---

Rules for 三:

• When followed by a counter starting with a は—column syllable, that syllable changes to a 'b' sound

---

Rules for 六:

• 
  

  When followed by a counter starting with a か—column syllable, ろく becomes ろっ

  
  


• 
  

  When followed by a counter starting with a は—column syllable, ろく becomes ろっ and the counter changes to a 'p' sound

  
  

---

Rules for 八:

• 
  

  When followed by a counter starting with a か—, さ— or た—column syllable, はち becomes はっ

  
  


• 
  

  When followed by a counter starting with a は—column syllable, はち becomes はっ and the counter changes to a 'p' sound

  
  

---

Rules for 十:

• 
  

  When followed by a counter starting with a か—, さ— or た—column syllable, じゅう may become じっ or じゅっ

  
  


• 
  

  When followed by a counter starting with a は—column syllable, じゅう can become either じっ or じゅっ and the counter changes to a 'p' sound

  
  

---

In short I don't think it matters if the counter is of Japanese origin or foreign origin. It depends on the first syllable of the counter.