In principle it does not matter whether one receives the immunoglobulins one needs to prevent episodes of SCLS intravenously (IVIG) or subcutaneously (SCIG). The practical issue is that SCIG is capable of delivering a much smaller amount of IG than IVIG can deliver. There is only so much SCIG that a patient's skin and muscles can absorb at each spot without causing unbearable pain, and only so many times per week that patients are willing to shoot themselves with needles in order to receive the dose of SCIG they require -- especially when the body can absorb virtually unlimited amounts of IG when delivered intravenously. This is why SCIG is usually only given to, and tolerated by, children with SCLS -- especially those for which lower doses have the desired effect.
For example, if a 10-year old child weighs a typical 30 kilos and needs 2 gr/kg/month, or a total of 60 grams, that is an amount that can reasonably be delivered either via IVIG (over two days) or SCIG (over many days). Even better, of course, if the 30-kilo child only needs 1 gr/kg/month, in which case only 30 grams need to be delivered via IVIG (over two days) or SCIG (over many days). That is usually tolerable and achievable either way.
However, if an adult weighs a typical 60-100 kilos and needs 2 gr/kg/month, or a total of 120-200 grams, that is an amount that usually cannot reasonably be delivered, absorbed, and thus tolerated via SCIG even when spread out over most days.
Of course, you should not rely on what I just wrote, and you should discuss this practical aspect with your physician and infusion nurse -- especially now that you went through the trouble and risk of having a port, as per your other thread.
If I were you, I would first make absolutely sure that I could not tolerate receiving my IVIG in two days rather than three, which is the normal, thereby cutting out one trip per month to your current infusion center. And second, I would make sure that I could not receive my IVIG from an infusion center located closer to my home. These centers typically cater to cancer patients -- and unfortunately there are a lot of cancer patients everywhere.