am I eligible for ILR with a gap of 6 months

[boyala24]

I am on work permit + Tier 1 for below period.

Work permit -- Feb 12th 2006 to Aug 2008
Tier 1 : Aug 2008 to Valid till Aug 2011.

But I am completing 5 years by 12th Feb 2011 which makes me eligible for ILR.
But issue is I was away for 6 month 5 days during my initial year 2006. (between May 12 2006 to 16th Nov 2006)
This trip was based on my employer assignment purpose at aboard. During this period I am holding the same UK WP working for the same employer in aboard. but my salary was paid in aboard as the employer has branch in that country.
My previous employer is ready to give a letter stating that trip is for business purpose.

Am I eligible to apply for ILR in Feb 2011 or do I need to wait for 6 months to cover this gap period. If I am eligible what would be the list of documents I need to provide to support this case.
Some one please guide me.

Thanks in advance