Yep it is possible.
I did all my ATPL theory CPL, ME, FI, and IR all at weekends and during annual leave from my full time job as a project engineer. Just find and FTO that has the flexibility to work with your availability.
I started the IR on the 6th December 2005 and completed on the 18th April 2006, (could have been sooner if it wasnt for the weather). I flew friday afternoons the odd saturday (when the weather was crap and couldnt teach PPL so I would go and do some IR sim work) all day sunday and I only took 2 days leave from my full time job. It was a busy time for me but I still managed a first time pass. So all in all it do-able but hard work
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All the best Mint