for dividing your stitches onto dpn's (5 is good in this case)
circ 1: divide these stitches evenly between dpn1 and dpn2
circ 2: divide these stitches evenly between dpn3 and dpn4 (I have not seen the pattern, but assume the cable is worked on circ 2- in this case I would not use 5 needles, I would use four and put all the stitches for circ 2 on dpn3.)
Next rnd: Work to last 7 sts of Needle 1, with wy p7, slip these 7 sts to LH needle and p7 with working yarn; work to end of rnd.
rewritten for dpns...Work to last 7 sts of dpn2, with waste yarn p7, slip these 7 sts to LH needle and p7 with working yarn. (This is basically holding the stitches that will become the thumb hole. You purl them with waste yarn to mark the spot, put them back on the lh needle and work them again so you can continue working the rest of the glove without breaking your yarn.)
When you remove the waste yarn you are left with a opening for the thumb.
I have no idea what '5im3w' means...can you tell me what the abbreviations stand for and I can help with the rest...