[R] changing default labels of axis in ts plots

[javier garcia - CEBAS]

Hi;
I'm in Spain and my locale and tz are the spanish one, and I'm using plot() 
with irregular time series. And I would like to change the default labels in 
x and y axis:

1) The labels of months in the x axis of the plots appear in Spanish -  
c("Enero,"Febrero",...) - and I would like them to appear in English - 
c("January","February",...) - without changing the locale settings of my 
computer.

2) Also, the labels refers to local time and I would like them to appear in 
UTC ("GMT") time.

I've tried, in several ways, to pass the format and timezone "GMT" to the 
plot, with no result.

Could these defaults be changed without a big effort?

Thanks and best regards

Javier G.