I have a Prosport Boost Guage which just ducts boost to the sensor unit bolted onto the firewall and then electric leads run to the dash mounted guage.
But there is no problem running the boost vac line from the BOV cap to the back of a guage via a small hole drilled in the LH bulkhead behind the glovebox then across the dash over the "transmission hump" and up the RH side of the dash to the A-pillar. All my other stuff follows that route and is easily hidden behind the door frame rubber. Be careful not to kink or restrict the vacuum line though. This LH route keeps the line away from the hotter side of the engine bay and provides easier access to drill a small grommeted port to pass the line through. If you keep the line cooler it is less likely to kink or collapse. I must admit I prefer the electric connection as it reduces the length of the vac line.
CP_e Standback & PNP; CP_e 3" SS Downpipe; Corksport FMIC with Top-mount K&N filter & OEM Ram CAI; Turbosmart BOV; Dashhawk; Prosport Boost Guage; JBR solid shift bushes; DBA 4000 Wiper-Slot front rotors; Hawk Ferro-Carbon HPS Street front brake pads (@ 69,000km); Sumitomo HTRZIII's in 225/45 x 18