thread through the grommet behind the DV. You only need to remove the lower dash cover - torx screws underneath and on the side under the fuse box cover.
Depending on which pod you are using you may or may not have to drill the A-pillar.
If you buy a Nomad pillar be careful as some people (including me) have had fitment problems. They are 50 quid and made of fibreglass, not worth it IMO. Also the gauge pod depth is very shallow you may have problems getting the boost gauge to sit inside properly. My VDO gauge would not fit at all.
I don't mean to put you off though some people are happy with their nomad pillars, to me its not a "finished" product. It looks crude and only comes with sticky-backed velcro to stick it in, very unlike the OEM pillar which has 5 firm clips, and a strip of velvet at the bottom.