Shell1 - if you are getting sore and swollen, then I'd maybe suggest that you stop. Swollen tissue can't stretch very well. I've heard of women using a bit of massage oil in labour as the head descends to add a bit of lubrication if they want, or just stick with the warm compresses/warm water. If the perineum is supported and the head emerges in a controlled way (ie. BREATHE it out if you can), that will be your best help.
All the best!