I build my own DRL using a set of clear reflectors, and also bought a set of DLR controller from China. Installed everything and no issues for the past 6 months or more, hence from my experience (2004 UK GT model), this should not be an issue.
I use these T-tap by 3M --> http://solutions.3m.co.uk/wps/portal/3M/en_GB/ElectricalMkts/ElectricalSupplies/products/scotchlok-wire-connectors/scotchlok-electrical-idc-wire-connectors/scotchlok-952-t-tap-disconnect/ to tap into side light harness. It can be removed easily if needed and just cover the original harness with insulation tape. Alternatively, if you want to try, use needle to pierce through the harness to gain connection. If it doesn't work, a needle hole can be easily sealed/covered.
Have fun!!